[ Upstream commit 1532b97784 ]
DSA network devices rely on having their DSA management interface up and
running otherwise their ndo_open() will return -ENETDOWN. Without doing
this it would not be possible to use DSA devices as netconsole when
configured on the command line. These devices also do not utilize the
upper/lower linking so the check about the netpoll device having upper
is not going to be a problem.
The solution adopted here is identical to the one done for
net/ipv4/ipconfig.c with 728c02089a ("net: ipv4: handle DSA enabled
master network devices"), with the network namespace scope being
restricted to that of the process configuring netpoll.
Fixes: 04ff53f96a ("net: dsa: Add netconsole support")
Tested-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20201117035236.22658-1-f.fainelli@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 92307069a9 ]
As soon as you add the second port to a VLAN, all other port
membership configuration is overwritten with zeroes. The HW interprets
this as all ports being "unmodified members" of the VLAN.
In the simple case when all ports belong to the same VLAN, switching
will still work. But using multiple VLANs or trying to set multiple
ports as tagged members will not work.
On the 6352, doing a VTU GetNext op, followed by an STU GetNext op
will leave you with both the member- and state- data in the VTU/STU
data registers. But on the 6097 (which uses the same implementation),
the STU GetNext will override the information gathered from the VTU
GetNext.
Separate the two stages, parsing the result of the VTU GetNext before
doing the STU GetNext.
We opt to update the existing implementation for all applicable chips,
as opposed to creating a separate callback for 6097, because although
the previous implementation did work for (at least) 6352, the
datasheet does not mention the masking behavior.
Fixes: ef6fcea37f ("net: dsa: mv88e6xxx: get STU entry on VTU GetNext")
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Link: https://lore.kernel.org/r/20201112114335.27371-1-tobias@waldekranz.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 1f492eab67 ]
The driver sends Ethernet Management Datagram (EMAD) packets to the
device for configuration purposes and waits for up to 200ms for a reply.
A request is retried up to 5 times.
When the system is under heavy load, replies are not always processed in
time and EMAD transactions fail.
Make the process more robust to such delays by using exponential
backoff. First wait for up to 200ms, then retransmit and wait for up to
400ms and so on.
Fixes: caf7297e7a ("mlxsw: core: Introduce support for asynchronous EMAD register access")
Reported-by: Denis Yulevich <denisyu@nvidia.com>
Tested-by: Denis Yulevich <denisyu@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 796a2665ca ]
On arm imx6, when opening the chip's netdev, the whole Linux
kernel intermittently hangs/freezes.
This is caused by a bug in the driver code which tests if pcie
interrupts are working correctly, using the software interrupt:
1. open: enable the software interrupt
2. open: tell the chip to assert the software interrupt
3. open: wait for flag
4. ISR: acknowledge s/w interrupt, set flag
5. open: notice flag, disable the s/w interrupt, continue
Unfortunately the ISR only acknowledges the s/w interrupt, but
does not disable it. This will re-trigger the ISR in a tight
loop.
On some (lucky) platforms, open proceeds to disable the s/w
interrupt even while the ISR is 'spinning'. On arm imx6,
the spinning ISR does not allow open to proceed, resulting
in a hung Linux kernel.
Fix minimally by disabling the s/w interrupt in the ISR, which
will prevent it from spinning. This won't break anything because
the s/w interrupt is used as a one-shot interrupt.
Note that this is a minimal fix, overlooking many possible
cleanups, e.g.:
- lan743x_intr_software_isr() is completely redundant and reads
INT_STS twice for no apparent reason
- disabling the s/w interrupt in lan743x_intr_test_isr() is now
redundant, but harmless
- waiting on software_isr_flag can be converted from a sleeping
poll loop to wait_event_timeout()
Fixes: 23f0703c12 ("lan743x: Add main source files for new lan743x driver")
Tested-by: Sven Van Asbroeck <thesven73@gmail.com> # arm imx6 lan7430
Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
Link: https://lore.kernel.org/r/20201112204741.12375-1-TheSven73@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit e35df62e04 ]
When running this chip on arm imx6, we intermittently observe
the following kernel warning in the log, especially when the
system is under high load:
[ 50.119484] ------------[ cut here ]------------
[ 50.124377] WARNING: CPU: 0 PID: 303 at kernel/softirq.c:169 __local_bh_enable_ip+0x100/0x184
[ 50.132925] IRQs not enabled as expected
[ 50.159250] CPU: 0 PID: 303 Comm: rngd Not tainted 5.7.8 #1
[ 50.164837] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 50.171395] [<c0111a38>] (unwind_backtrace) from [<c010be28>] (show_stack+0x10/0x14)
[ 50.179162] [<c010be28>] (show_stack) from [<c05b9dec>] (dump_stack+0xac/0xd8)
[ 50.186408] [<c05b9dec>] (dump_stack) from [<c0122e40>] (__warn+0xd0/0x10c)
[ 50.193391] [<c0122e40>] (__warn) from [<c0123238>] (warn_slowpath_fmt+0x98/0xc4)
[ 50.200892] [<c0123238>] (warn_slowpath_fmt) from [<c012b010>] (__local_bh_enable_ip+0x100/0x184)
[ 50.209860] [<c012b010>] (__local_bh_enable_ip) from [<bf09ecbc>] (destroy_conntrack+0x48/0xd8 [nf_conntrack])
[ 50.220038] [<bf09ecbc>] (destroy_conntrack [nf_conntrack]) from [<c0ac9b58>] (nf_conntrack_destroy+0x94/0x168)
[ 50.230160] [<c0ac9b58>] (nf_conntrack_destroy) from [<c0a4aaa0>] (skb_release_head_state+0xa0/0xd0)
[ 50.239314] [<c0a4aaa0>] (skb_release_head_state) from [<c0a4aadc>] (skb_release_all+0xc/0x24)
[ 50.247946] [<c0a4aadc>] (skb_release_all) from [<c0a4b4cc>] (consume_skb+0x74/0x17c)
[ 50.255796] [<c0a4b4cc>] (consume_skb) from [<c081a2dc>] (lan743x_tx_release_desc+0x120/0x124)
[ 50.264428] [<c081a2dc>] (lan743x_tx_release_desc) from [<c081a98c>] (lan743x_tx_napi_poll+0x5c/0x18c)
[ 50.273755] [<c081a98c>] (lan743x_tx_napi_poll) from [<c0a6b050>] (net_rx_action+0x118/0x4a4)
[ 50.282306] [<c0a6b050>] (net_rx_action) from [<c0101364>] (__do_softirq+0x13c/0x53c)
[ 50.290157] [<c0101364>] (__do_softirq) from [<c012b29c>] (irq_exit+0x150/0x17c)
[ 50.297575] [<c012b29c>] (irq_exit) from [<c0196a08>] (__handle_domain_irq+0x60/0xb0)
[ 50.305423] [<c0196a08>] (__handle_domain_irq) from [<c05d44fc>] (gic_handle_irq+0x4c/0x90)
[ 50.313790] [<c05d44fc>] (gic_handle_irq) from [<c0100ed4>] (__irq_usr+0x54/0x80)
[ 50.321287] Exception stack(0xecd99fb0 to 0xecd99ff8)
[ 50.326355] 9fa0: 1cf1aa74 00000001 00000001 00000000
[ 50.334547] 9fc0: 00000001 00000000 00000000 00000000 00000000 00000000 00004097 b6d17d14
[ 50.342738] 9fe0: 00000001 b6d17c60 00000000 b6e71f94 800b0010 ffffffff
[ 50.349364] irq event stamp: 2525027
[ 50.352955] hardirqs last enabled at (2525026): [<c0a6afec>] net_rx_action+0xb4/0x4a4
[ 50.360892] hardirqs last disabled at (2525027): [<c0d6d2fc>] _raw_spin_lock_irqsave+0x1c/0x50
[ 50.369517] softirqs last enabled at (2524660): [<c01015b4>] __do_softirq+0x38c/0x53c
[ 50.377446] softirqs last disabled at (2524693): [<c012b29c>] irq_exit+0x150/0x17c
[ 50.385027] ---[ end trace c0b571db4bc8087d ]---
The driver is calling dev_kfree_skb() from code inside a spinlock,
where h/w interrupts are disabled. This is forbidden, as documented
in include/linux/netdevice.h. The correct function to use
dev_kfree_skb_irq(), or dev_kfree_skb_any().
Fix by using the correct dev_kfree_skb_xxx() functions:
in lan743x_tx_release_desc():
called by lan743x_tx_release_completed_descriptors()
called by in lan743x_tx_napi_poll()
which holds a spinlock
called by lan743x_tx_release_all_descriptors()
called by lan743x_tx_close()
which can-sleep
conclusion: use dev_kfree_skb_any()
in lan743x_tx_xmit_frame():
which holds a spinlock
conclusion: use dev_kfree_skb_irq()
in lan743x_tx_close():
which can-sleep
conclusion: use dev_kfree_skb()
in lan743x_rx_release_ring_element():
called by lan743x_rx_close()
which can-sleep
called by lan743x_rx_open()
which can-sleep
conclusion: use dev_kfree_skb()
Fixes: 23f0703c12 ("lan743x: Add main source files for new lan743x driver")
Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
Link: https://lore.kernel.org/r/20201112185949.11315-1-TheSven73@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 4260330b32 ]
The module eeprom address range returned by bnxt_get_module_eeprom()
should be 256 bytes of A0h address space, the lower half of the A2h
address space, and page 0 for the upper half of the A2h address space.
Fix the firmware call by passing page_number 0 for the A2h slave address
space.
Fixes: 42ee18fe4c ("bnxt_en: Add Support for ETHTOOL_GMODULEINFO and ETHTOOL_GMODULEEEPRO")
Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 6dceaa9f56 ]
The `skb' is mapped for DMA in ns_send() but does not unmap DMA in case
push_scqe() fails to submit the `skb'. The memory of the `skb' is
released so only the DMA mapping is leaking.
Unmap the DMA mapping in case push_scqe() failed.
Fixes: 864a3ff635 ("atm: [nicstar] remove virt_to_bus() and support 64-bit platforms")
Cc: Chas Williams <3chas3@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 9debfb81e7 upstream.
Clang is more aggressive about -Wformat warnings when the format flag
specifies a type smaller than the parameter. It turns out that gsi is an
int. Fixes:
drivers/acpi/evged.c:105:48: warning: format specifies type 'unsigned
char' but the argument has type 'unsigned int' [-Wformat]
trigger == ACPI_EDGE_SENSITIVE ? 'E' : 'L', gsi);
^~~
Link: https://github.com/ClangBuiltLinux/linux/issues/378
Fixes: ea6f3af4c5 ("ACPI: GED: add support for _Exx / _Lxx handler methods")
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit dcd479e10a upstream.
When (for example) an IBSS station is pre-moved to AUTHORIZED
before it's inserted, and then the insertion fails, we don't
clean up the fast RX/TX states that might already have been
created, since we don't go through all the state transitions
again on the way down.
Do that, if it hasn't been done already, when the station is
freed. I considered only freeing the fast TX/RX state there,
but we might add more state so it's more robust to wind down
the state properly.
Note that we warn if the station was ever inserted, it should
have been properly cleaned up in that case, and the driver
will probably not like things happening out of order.
Reported-by: syzbot+2e293dbd67de2836ba42@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20201009141710.7223b322a955.I95bd08b9ad0e039c034927cce0b75beea38e059b@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 29daf869cb upstream.
The kernel expects pte_young() to work regardless of CONFIG_SWAP.
Make sure a minor fault is taken to set _PAGE_ACCESSED when it
is not already set, regardless of the selection of CONFIG_SWAP.
This adds at least 3 instructions to the TLB miss exception
handlers fast path. Following patch will reduce this overhead.
Also update the rotation instruction to the correct number of bits
to reflect all changes done to _PAGE_ACCESSED over time.
Fixes: d069cb4373 ("powerpc/8xx: Don't touch ACCESSED when no SWAP.")
Fixes: 5f356497c3 ("powerpc/8xx: remove unused _PAGE_WRITETHRU")
Fixes: e0a8e0d90a ("powerpc/8xx: Handle PAGE_USER via APG bits")
Fixes: 5b2753fc3e ("powerpc/8xx: Implementation of PAGE_EXEC")
Fixes: a891c43b97 ("powerpc/8xx: Prepare handlers for _PAGE_HUGE for 512k pages.")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/af834e8a0f1fa97bfae65664950f0984a70c4750.1602492856.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 168200b6d6 upstream.
(but only from 4.19.y)
The original commit introduces a build failure as seen on Debian buster
when compiled with gcc (Debian 8.3.0-6) 8.3.0:
$ LC_ALL=C.UTF-8 ARCH=x86 make perf
[...]
Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf.h' differs from latest version at 'include/uapi/linux/bpf.h'
CC util/cs-etm-decoder/cs-etm-decoder.o
CC util/intel-pt.o
util/cs-etm-decoder/cs-etm-decoder.c: In function 'cs_etm_decoder__buffer_packet':
util/cs-etm-decoder/cs-etm-decoder.c:287:24: error: 'traceid_list' undeclared (first use in this function); did you mean 'trace_event'?
inode = intlist__find(traceid_list, trace_chan_id);
^~~~~~~~~~~~
trace_event
util/cs-etm-decoder/cs-etm-decoder.c:287:24: note: each undeclared identifier is reported only once for each function it appears in
make[6]: *** [/build/linux-stable/tools/build/Makefile.build:97: util/cs-etm-decoder/cs-etm-decoder.o] Error 1
make[5]: *** [/build/linux-stable/tools/build/Makefile.build:139: cs-etm-decoder] Error 2
make[5]: *** Waiting for unfinished jobs....
make[4]: *** [/build/linux-stable/tools/build/Makefile.build:139: util] Error 2
make[3]: *** [Makefile.perf:633: libperf-in.o] Error 2
make[2]: *** [Makefile.perf:206: sub-make] Error 2
make[1]: *** [Makefile:70: all] Error 2
make: *** [Makefile:77: perf] Error 2
Link: https://lore.kernel.org/stable/20201114083501.GA468764@eldamar.lan/
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Tor Jeremiassen <tor@ti.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org> # 4.19.y
Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 9a32a7e78b upstream.
IBM Power9 processors can speculatively operate on data in the L1 cache before
it has been completely validated, via a way-prediction mechanism. It is not possible
for an attacker to determine the contents of impermissible memory using this method,
since these systems implement a combination of hardware and software security measures
to prevent scenarios where protected data could be leaked.
However these measures don't address the scenario where an attacker induces
the operating system to speculatively execute instructions using data that the
attacker controls. This can be used for example to speculatively bypass "kernel
user access prevention" techniques, as discovered by Anthony Steinhauser of
Google's Safeside Project. This is not an attack by itself, but there is a possibility
it could be used in conjunction with side-channels or other weaknesses in the
privileged code to construct an attack.
This issue can be mitigated by flushing the L1 cache between privilege boundaries
of concern. This patch flushes the L1 cache after user accesses.
This is part of the fix for CVE-2020-4788.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit d02f6b7dab upstream.
get/put_user() can be called with nontrivial arguments. fs/proc/page.c
has a good example:
if (put_user(stable_page_flags(ppage), out)) {
stable_page_flags() is quite a lot of code, including spin locks in
the page allocator.
Ensure these arguments are evaluated before user access is allowed.
This improves security by reducing code with access to userspace, but
it also fixes a PREEMPT bug with KUAP on powerpc/64s:
stable_page_flags() is currently called with AMR set to allow writes,
it ends up calling spin_unlock(), which can call preempt_schedule. But
the task switch code can not be called with AMR set (it relies on
interrupts saving the register), so this blows up.
It's fine if the code inside allow_user_access() is preemptible,
because a timer or IPI will save the AMR, but it's not okay to
explicitly cause a reschedule.
Fixes: de78a9c42a ("powerpc: Add a framework for Kernel Userspace Access Protection")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200407041245.600651-1-npiggin@gmail.com
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 61e3acd8c6 upstream.
The KUAP implementation adds calls in clear_user() to enable and
disable access to userspace memory. However, it doesn't add these to
__clear_user(), which is used in the ptrace regset code.
As there's only one direct user of __clear_user() (the regset code),
and the time taken to set the AMR for KUAP purposes is going to
dominate the cost of a quick access_ok(), there's not much point
having a separate path.
Rename __clear_user() to __arch_clear_user(), and make __clear_user()
just call clear_user().
Reported-by: syzbot+f25ecf4b2982d8c7a640@syzkaller-ppc64.appspotmail.com
Reported-by: Daniel Axtens <dja@axtens.net>
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Fixes: de78a9c42a ("powerpc: Add a framework for Kernel Userspace Access Protection")
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
[mpe: Use __arch_clear_user() for the asm version like arm64 & nds32]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191209132221.15328-1-ajd@linux.ibm.com
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5cd623333e upstream.
Today, when a function like strncpy_from_user() is called,
the userspace access protection is de-activated and re-activated
for every word read.
By implementing user_access_begin and friends, the protection
is de-activated at the beginning of the copy and re-activated at the
end.
Implement user_access_begin(), user_access_end() and
unsafe_get_user(), unsafe_put_user() and unsafe_copy_to_user()
For the time being, we keep user_access_save() and
user_access_restore() as nops.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/36d4fbf9e56a75994aca4ee2214c77b26a5a8d35.1579866752.git.christophe.leroy@c-s.fr
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Backported from commit de78a9c42a ("powerpc: Add a framework
for Kernel Userspace Access Protection"). Here we don't try to
add the KUAP framework, we just want the helper functions
because we want to put uaccess flush helpers in them.
In terms of fixes, we don't need commit 1d8f739b07 ("powerpc/kuap:
Fix set direction in allow/prevent_user_access()") as we don't have
real KUAP. Likewise as all our allows are noops and all our prevents
are just flushes, we don't need commit 9dc086f1e9 ("powerpc/futex:
Fix incorrect user access blocking") The other 2 fixes we do need.
The original description is:
This patch implements a framework for Kernel Userspace Access
Protection.
Then subarches will have the possibility to provide their own
implementation by providing setup_kuap() and
allow/prevent_user_access().
Some platforms will need to know the area accessed and whether it is
accessed from read, write or both. Therefore source, destination and
size and handed over to the two functions.
mpe: Rename to allow/prevent rather than unlock/lock, and add
read/write wrappers. Drop the 32-bit code for now until we have an
implementation for it. Add kuap to pt_regs for 64-bit as well as
32-bit. Don't split strings, use pr_crit_ratelimited().
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit f79643787e upstream.
IBM Power9 processors can speculatively operate on data in the L1 cache before
it has been completely validated, via a way-prediction mechanism. It is not possible
for an attacker to determine the contents of impermissible memory using this method,
since these systems implement a combination of hardware and software security measures
to prevent scenarios where protected data could be leaked.
However these measures don't address the scenario where an attacker induces
the operating system to speculatively execute instructions using data that the
attacker controls. This can be used for example to speculatively bypass "kernel
user access prevention" techniques, as discovered by Anthony Steinhauser of
Google's Safeside Project. This is not an attack by itself, but there is a possibility
it could be used in conjunction with side-channels or other weaknesses in the
privileged code to construct an attack.
This issue can be mitigated by flushing the L1 cache between privilege boundaries
of concern. This patch flushes the L1 cache on kernel entry.
This is part of the fix for CVE-2020-4788.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(backport only)
We're about to grow the exception handlers, which will make a bunch of them
no longer fit within the space available. We move them out of line.
This is a fiddly and error-prone business, so in the interests of reviewability
I haven't merged this in with the addition of the entry flush.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 57c1760740 upstream.
When converting trailing spaces and periods in paths, do so
for every component of the path, not just the last component.
If the conversion is not done for every path component, then
subsequent operations in directories with trailing spaces or
periods (e.g. create(), mkdir()) will fail with ENOENT. This
is because on the server, the directory will have a special
symbol in its name, and the client needs to provide the same.
Signed-off-by: Boris Protopopov <pboris@amazon.com>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8b92c4ff44 upstream.
Patch series "fix parsing of reboot= cmdline", v3.
The parsing of the reboot= cmdline has two major errors:
- a missing bound check can crash the system on reboot
- parsing of the cpu number only works if specified last
Fix both.
This patch (of 2):
This reverts commit 616feab753.
kstrtoint() and simple_strtoul() have a subtle difference which makes
them non interchangeable: if a non digit character is found amid the
parsing, the former will return an error, while the latter will just
stop parsing, e.g. simple_strtoul("123xyx") = 123.
The kernel cmdline reboot= argument allows to specify the CPU used for
rebooting, with the syntax `s####` among the other flags, e.g.
"reboot=warm,s31,force", so if this flag is not the last given, it's
silently ignored as well as the subsequent ones.
Fixes: 616feab753 ("kernel/reboot.c: convert simple_strtoul to kstrtoint")
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201103214025.116799-2-mcroce@linux.microsoft.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[sudip: use reboot_mode instead of mode]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit f91072ed1b upstream.
There's a possible race in perf_mmap_close() when checking ring buffer's
mmap_count refcount value. The problem is that the mmap_count check is
not atomic because we call atomic_dec() and atomic_read() separately.
perf_mmap_close:
...
atomic_dec(&rb->mmap_count);
...
if (atomic_read(&rb->mmap_count))
goto out_put;
<ring buffer detach>
free_uid
out_put:
ring_buffer_put(rb); /* could be last */
The race can happen when we have two (or more) events sharing same ring
buffer and they go through atomic_dec() and then they both see 0 as refcount
value later in atomic_read(). Then both will go on and execute code which
is meant to be run just once.
The code that detaches ring buffer is probably fine to be executed more
than once, but the problem is in calling free_uid(), which will later on
demonstrate in related crashes and refcount warnings, like:
refcount_t: addition on 0; use-after-free.
...
RIP: 0010:refcount_warn_saturate+0x6d/0xf
...
Call Trace:
prepare_creds+0x190/0x1e0
copy_creds+0x35/0x172
copy_process+0x471/0x1a80
_do_fork+0x83/0x3a0
__do_sys_wait4+0x83/0x90
__do_sys_clone+0x85/0xa0
do_syscall_64+0x5b/0x1e0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Using atomic decrease and check instead of separated calls.
Tested-by: Michael Petlan <mpetlan@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Wade Mealing <wmealing@redhat.com>
Fixes: 9bb5d40cd9 ("perf: Fix mmap() accounting hole");
Link: https://lore.kernel.org/r/20200916115311.GE2301783@krava
[sudip: used ring_buffer]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit d0e7b0c71f upstream.
To avoid this:
util/scripting-engines/trace-event-python.c: In function 'python_start_script':
util/scripting-engines/trace-event-python.c:1595:2: error: 'visibility' attribute ignored [-Werror=attributes]
1595 | PyMODINIT_FUNC (*initfunc)(void);
| ^~~~~~~~~~~~~~
That started breaking when building with PYTHON=python3 and these gcc
versions (I haven't checked with the clang ones, maybe it breaks there
as well):
# export PERF_TARBALL=http://192.168.86.5/perf/perf-5.9.0.tar.xz
# dm fedora:33 fedora:rawhide
1 107.80 fedora:33 : Ok gcc (GCC) 10.2.1 20201005 (Red Hat 10.2.1-5), clang version 11.0.0 (Fedora 11.0.0-1.fc33)
2 92.47 fedora:rawhide : Ok gcc (GCC) 10.2.1 20201016 (Red Hat 10.2.1-6), clang version 11.0.0 (Fedora 11.0.0-1.fc34)
#
Avoid that by ditching that 'initfunc' function pointer with its:
#define Py_EXPORTED_SYMBOL _attribute_ ((visibility ("default")))
#define PyMODINIT_FUNC Py_EXPORTED_SYMBOL PyObject*
And just call PyImport_AppendInittab() at the end of the ifdef python3
block with the functions that were being attributed to that initfunc.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Tapas Kundu <tkundu@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 1978b3a53a upstream.
On AMD CPUs which have the feature X86_FEATURE_AMD_STIBP_ALWAYS_ON,
STIBP is set to on and
spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED
At the same time, IBPB can be set to conditional.
However, this leads to the case where it's impossible to turn on IBPB
for a process because in the PR_SPEC_DISABLE case in ib_prctl_set() the
spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED
condition leads to a return before the task flag is set. Similarly,
ib_prctl_get() will return PR_SPEC_DISABLE even though IBPB is set to
conditional.
More generally, the following cases are possible:
1. STIBP = conditional && IBPB = on for spectre_v2_user=seccomp,ibpb
2. STIBP = on && IBPB = conditional for AMD CPUs with
X86_FEATURE_AMD_STIBP_ALWAYS_ON
The first case functions correctly today, but only because
spectre_v2_user_ibpb isn't updated to reflect the IBPB mode.
At a high level, this change does one thing. If either STIBP or IBPB
is set to conditional, allow the prctl to change the task flag.
Also, reflect that capability when querying the state. This isn't
perfect since it doesn't take into account if only STIBP or IBPB is
unconditionally on. But it allows the conditional feature to work as
expected, without affecting the unconditional one.
[ bp: Massage commit message and comment; space out statements for
better readability. ]
Fixes: 21998a3515 ("x86/speculation: Avoid force-disabling IBPB based on STIBP and enhanced IBRS.")
Signed-off-by: Anand K Mistry <amistry@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20201105163246.v2.1.Ifd7243cd3e2c2206a893ad0a5b9a4f19549e22c6@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c51f8f88d7 upstream.
Non-cryptographic PRNGs may have great statistical properties, but
are usually trivially predictable to someone who knows the algorithm,
given a small sample of their output. An LFSR like prandom_u32() is
particularly simple, even if the sample is widely scattered bits.
It turns out the network stack uses prandom_u32() for some things like
random port numbers which it would prefer are *not* trivially predictable.
Predictability led to a practical DNS spoofing attack. Oops.
This patch replaces the LFSR with a homebrew cryptographic PRNG based
on the SipHash round function, which is in turn seeded with 128 bits
of strong random key. (The authors of SipHash have *not* been consulted
about this abuse of their algorithm.) Speed is prioritized over security;
attacks are rare, while performance is always wanted.
Replacing all callers of prandom_u32() is the quick fix.
Whether to reinstate a weaker PRNG for uses which can tolerate it
is an open question.
Commit f227e3ec3b ("random32: update the net random state on interrupt
and activity") was an earlier attempt at a solution. This patch replaces
it.
Reported-by: Amit Klein <aksecurity@gmail.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: tytso@mit.edu
Cc: Florian Westphal <fw@strlen.de>
Cc: Marc Plumb <lkml.mplumb@gmail.com>
Fixes: f227e3ec3b ("random32: update the net random state on interrupt and activity")
Signed-off-by: George Spelvin <lkml@sdf.org>
Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/
[ willy: partial reversal of f227e3ec3b5c; moved SIPROUND definitions
to prandom.h for later use; merged George's prandom_seed() proposal;
inlined siprand_u32(); replaced the net_rand_state[] array with 4
members to fix a build issue; cosmetic cleanups to make checkpatch
happy; fixed RANDOM32_SELFTEST build ]
[wt: backported to 4.19 -- various context adjustments]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 9e2b7fa2df ]
VRF devices use an optimized direct path on output if a default qdisc
is involved, calling Netfilter hooks directly. This path, however, does
not consider Netfilter rules completing asynchronously, such as with
NFQUEUE. The Netfilter okfn() is called for asynchronously accepted
packets, but the VRF never passes that packet down the stack to send
it out over the slave device. Using the slower redirect path for this
seems not feasible, as we do not know beforehand if a Netfilter hook
has asynchronously completing rules.
Fix the use of asynchronously completing Netfilter rules in OUTPUT and
POSTROUTING by using a special completion function that additionally
calls dst_output() to pass the packet down the stack. Also, slightly
adjust the use of nf_reset_ct() so that is called in the asynchronous
case, too.
Fixes: dcdd43c41e ("net: vrf: performance improvements for IPv4")
Fixes: a9ec54d1b0 ("net: vrf: performance improvements for IPv6")
Signed-off-by: Martin Willi <martin@strongswan.org>
Link: https://lore.kernel.org/r/20201106073030.3974927-1-martin@strongswan.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 3611823087 ]
This fixes a regression for blocking connects introduced by commit
4becb7ee5b ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect").
The x25->neighbour is already set to "NULL" by x25_disconnect() now,
while a blocking connect is waiting in
x25_wait_for_connection_establishment(). Therefore x25->neighbour must
not be accessed here again and x25->state is also already set to
X25_STATE_0 by x25_disconnect().
Fixes: 4becb7ee5b ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect")
Signed-off-by: Martin Schiller <ms@dev.tdt.de>
Reviewed-by: Xie He <xie.he.0141@gmail.com>
Link: https://lore.kernel.org/r/20201109065449.9014-1-ms@dev.tdt.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 909172a149 ]
When net.ipv4.tcp_syncookies=1 and syn flood is happened,
cookie_v4_check or cookie_v6_check tries to redo what
tcp_v4_send_synack or tcp_v6_send_synack did,
rsk_window_clamp will be changed if SOCK_RCVBUF is set,
which will make rcv_wscale is different, the client
still operates with initial window scale and can overshot
granted window, the client use the initial scale but local
server use new scale to advertise window value, and session
work abnormally.
Fixes: e88c64f0a4 ("tcp: allow effective reduction of TCP's rcv-buffer via setsockopt")
Signed-off-by: Mao Wenan <wenan.mao@linux.alibaba.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/1604967391-123737-1-git-send-email-wenan.mao@linux.alibaba.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 4031eeafa7 ]
syzbot reported the following KASAN finding:
BUG: KASAN: nullptr-dereference in iucv_send_ctrl+0x390/0x3f0 net/iucv/af_iucv.c:385
Read of size 2 at addr 000000000000021e by task syz-executor907/519
CPU: 0 PID: 519 Comm: syz-executor907 Not tainted 5.9.0-syzkaller-07043-gbcf9877ad213 #0
Hardware name: IBM 3906 M04 701 (KVM/Linux)
Call Trace:
[<00000000c576af60>] unwind_start arch/s390/include/asm/unwind.h:65 [inline]
[<00000000c576af60>] show_stack+0x180/0x228 arch/s390/kernel/dumpstack.c:135
[<00000000c9dcd1f8>] __dump_stack lib/dump_stack.c:77 [inline]
[<00000000c9dcd1f8>] dump_stack+0x268/0x2f0 lib/dump_stack.c:118
[<00000000c5fed016>] print_address_description.constprop.0+0x5e/0x218 mm/kasan/report.c:383
[<00000000c5fec82a>] __kasan_report mm/kasan/report.c:517 [inline]
[<00000000c5fec82a>] kasan_report+0x11a/0x168 mm/kasan/report.c:534
[<00000000c98b5b60>] iucv_send_ctrl+0x390/0x3f0 net/iucv/af_iucv.c:385
[<00000000c98b6262>] iucv_sock_shutdown+0x44a/0x4c0 net/iucv/af_iucv.c:1457
[<00000000c89d3a54>] __sys_shutdown+0x12c/0x1c8 net/socket.c:2204
[<00000000c89d3b70>] __do_sys_shutdown net/socket.c:2212 [inline]
[<00000000c89d3b70>] __s390x_sys_shutdown+0x38/0x48 net/socket.c:2210
[<00000000c9e36eac>] system_call+0xe0/0x28c arch/s390/kernel/entry.S:415
There is nothing to shutdown if a connection has never been established.
Besides that iucv->hs_dev is not yet initialized if a socket is in
IUCV_OPEN state and iucv->path is not yet initialized if socket is in
IUCV_BOUND state.
So, just skip the shutdown calls for a socket in these states.
Fixes: eac3731bd0 ("[S390]: Add AF_IUCV socket support")
Fixes: 82492a355f ("af_iucv: add shutdown for HS transport")
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
[jwi: correct one Fixes tag]
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 8ef9ba4d66 ]
Due to the legacy usage of hard_header_len for SIT tunnels while
already using infrastructure from net/ipv4/ip_tunnel.c the
calculation of the path MTU in tnl_update_pmtu is incorrect.
This leads to unnecessary creation of MTU exceptions for any
flow going over a SIT tunnel.
As SIT tunnels do not have a header themsevles other than their
transport (L3, L2) headers we're leaving hard_header_len set to zero
as tnl_update_pmtu is already taking care of the transport headers
sizes.
This will also help avoiding unnecessary IPv6 GC runs and spinlock
contention seen when using SIT tunnels and for more than
net.ipv6.route.gc_thresh flows.
Fixes: c544193214 ("GRE: Refactor GRE tunneling code.")
Signed-off-by: Oliver Herms <oliver.peter.herms@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20201103104133.GA1573211@tws
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e9696d259d upstream.
kernel/dma/swiotlb.c:swiotlb_init gets called first and tries to
allocate a buffer for the swiotlb. It does so by calling
memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE);
If the allocation must fail, no_iotlb_memory is set.
Later during initialization swiotlb-xen comes in
(drivers/xen/swiotlb-xen.c:xen_swiotlb_init) and given that io_tlb_start
is != 0, it thinks the memory is ready to use when actually it is not.
When the swiotlb is actually needed, swiotlb_tbl_map_single gets called
and since no_iotlb_memory is set the kernel panics.
Instead, if swiotlb-xen.c:xen_swiotlb_init knew the swiotlb hadn't been
initialized, it would do the initialization itself, which might still
succeed.
Fix the panic by setting io_tlb_start to 0 on swiotlb initialization
failure, and also by setting no_iotlb_memory to false on swiotlb
initialization success.
Fixes: ac2cbab21f ("x86: Don't panic if can not alloc buffer for swiotlb")
Reported-by: Elliott Mitchell <ehem+xen@m5p.com>
Tested-by: Elliott Mitchell <ehem+xen@m5p.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit d3938ee23e upstream.
EROFS has _only one_ ondisk timestamp (ctime is currently
documented and recorded, we might also record mtime instead
with a new compat feature if needed) for each extended inode
since EROFS isn't mainly for archival purposes so no need to
keep all timestamps on disk especially for Android scenarios
due to security concerns. Also, romfs/cramfs don't have their
own on-disk timestamp, and squashfs only records mtime instead.
Let's also derive access time from ondisk timestamp rather than
leaving it empty, and if mtime/atime for each file are really
needed for specific scenarios as well, we can also use xattrs
to record them then.
Link: https://lore.kernel.org/r/20201031195102.21221-1-hsiangkao@aol.com
[ Gao Xiang: It'd be better to backport for user-friendly concern. ]
Fixes: 431339ba90 ("staging: erofs: add inode operations")
Cc: stable <stable@vger.kernel.org> # 4.19+
Reported-by: nl6720 <nl6720@gmail.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
[ Gao Xiang: Manually backport to 4.19.y due to trivial conflicts. ]
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 06ad8d3395 upstream.
The gma500 driver expects 3 pipelines in several it's IRQ functions.
Accessing struct drm_device.vblank[], this fails with devices that only
have 2 pipelines. An example KASAN report is shown below.
[ 62.267688] ==================================================================
[ 62.268856] BUG: KASAN: slab-out-of-bounds in psb_irq_postinstall+0x250/0x3c0 [gma500_gfx]
[ 62.269450] Read of size 1 at addr ffff8880012bc6d0 by task systemd-udevd/285
[ 62.269949]
[ 62.270192] CPU: 0 PID: 285 Comm: systemd-udevd Tainted: G E 5.10.0-rc1-1-default+ #572
[ 62.270807] Hardware name: /DN2800MT, BIOS MTCDT10N.86A.0164.2012.1213.1024 12/13/2012
[ 62.271366] Call Trace:
[ 62.271705] dump_stack+0xae/0xe5
[ 62.272180] print_address_description.constprop.0+0x17/0xf0
[ 62.272987] ? psb_irq_postinstall+0x250/0x3c0 [gma500_gfx]
[ 62.273474] __kasan_report.cold+0x20/0x38
[ 62.273989] ? psb_irq_postinstall+0x250/0x3c0 [gma500_gfx]
[ 62.274460] kasan_report+0x3a/0x50
[ 62.274891] psb_irq_postinstall+0x250/0x3c0 [gma500_gfx]
[ 62.275380] drm_irq_install+0x131/0x1f0
<...>
[ 62.300751] Allocated by task 285:
[ 62.301223] kasan_save_stack+0x1b/0x40
[ 62.301731] __kasan_kmalloc.constprop.0+0xbf/0xd0
[ 62.302293] drmm_kmalloc+0x55/0x100
[ 62.302773] drm_vblank_init+0x77/0x210
Resolve the issue by only handling vblank entries up to the number of
CRTCs.
I'm adding a Fixes tag for reference, although the bug has been present
since the driver's initial commit.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Fixes: 5c49fd3aa0 ("gma500: Add the core DRM files and headers")
Cc: Alan Cox <alan@linux.intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Cc: stable@vger.kernel.org#v3.3+
Link: https://patchwork.freedesktop.org/patch/msgid/20201105190256.3893-1-tzimmermann@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 77f6ab8b77 upstream.
Coredump logics needs to report not only the registers of the dumping
thread, but (since 2.5.43) those of other threads getting killed.
Doing that might require extra state saved on the stack in asm glue at
kernel entry; signal delivery logics does that (we need to be able to
save sigcontext there, at the very least) and so does seccomp.
That covers all callers of do_coredump(). Secondary threads get hit with
SIGKILL and caught as soon as they reach exit_mm(), which normally happens
in signal delivery, so those are also fine most of the time. Unfortunately,
it is possible to end up with secondary zapped when it has already entered
exit(2) (or, worse yet, is oopsing). In those cases we reach exit_mm()
when mm->core_state is already set, but the stack contents is not what
we would have in signal delivery.
At least on two architectures (alpha and m68k) it leads to infoleaks - we
end up with a chunk of kernel stack written into coredump, with the contents
consisting of normal C stack frames of the call chain leading to exit_mm()
instead of the expected copy of userland registers. In case of alpha we
leak 312 bytes of stack. Other architectures (including the regset-using
ones) might have similar problems - the normal user of regsets is ptrace
and the state of tracee at the time of such calls is special in the same
way signal delivery is.
Note that had the zapper gotten to the exiting thread slightly later,
it wouldn't have been included into coredump anyway - we skip the threads
that have already cleared their ->mm. So let's pretend that zapper always
loses the race. IOW, have exit_mm() only insert into the dumper list if
we'd gotten there from handling a fatal signal[*]
As the result, the callers of do_exit() that have *not* gone through get_signal()
are not seen by coredump logics as secondary threads. Which excludes voluntary
exit()/oopsen/traps/etc. The dumper thread itself is unaffected by that,
so seccomp is fine.
[*] originally I intended to add a new flag in tsk->flags, but ebiederman pointed
out that PF_SIGNALED is already doing just what we need.
Cc: stable@vger.kernel.org
Fixes: d89f3847def4 ("[PATCH] thread-aware coredumps, 2.5.43-C3")
History-tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
