[ Upstream commit c9484b986e ]
Patch series "kcov: fix unexpected faults".
These patches fix a few issues where KCOV code could trigger recursive
faults, discovered while debugging a patch enabling KCOV for arch/arm:
* On CONFIG_PREEMPT kernels, there's a small race window where
__sanitizer_cov_trace_pc() can see a bogus kcov_area.
* Lazy faulting of the vmalloc area can cause mutual recursion between
fault handling code and __sanitizer_cov_trace_pc().
* During the context switch, switching the mm can cause the kcov_area to
be transiently unmapped.
These are prerequisites for enabling KCOV on arm, but the issues
themsevles are generic -- we just happen to avoid them by chance rather
than design on x86-64 and arm64.
This patch (of 3):
For kernels built with CONFIG_PREEMPT, some C code may execute before or
after the interrupt handler, while the hardirq count is zero. In these
cases, in_task() can return true.
A task can be interrupted in the middle of a KCOV_DISABLE ioctl while it
resets the task's kcov data via kcov_task_init(). Instrumented code
executed during this period will call __sanitizer_cov_trace_pc(), and as
in_task() returns true, will inspect t->kcov_mode before trying to write
to t->kcov_area.
In kcov_init_task() we update t->kcov_{mode,area,size} with plain stores,
which may be re-ordered, torn, etc. Thus __sanitizer_cov_trace_pc() may
see bogus values for any of these fields, and may attempt to write to
memory which is not mapped.
Let's avoid this by using WRITE_ONCE() to set t->kcov_mode, with a
barrier() to ensure this is ordered before we clear t->kov_{area,size}.
This ensures that any code execute while kcov_init_task() is preempted
will either see valid values for t->kcov_{area,size}, or will see that
t->kcov_mode is KCOV_MODE_DISABLED, and bail out without touching
t->kcov_area.
Link: http://lkml.kernel.org/r/20180504135535.53744-2-mark.rutland@arm.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Changes in 4.9.84
vhost: use mutex_lock_nested() in vhost_dev_lock_vqs()
kcm: Check if sk_user_data already set in kcm_attach
kcm: Only allow TCP sockets to be attached to a KCM mux
cfg80211: check dev_set_name() return value
xfrm: skip policies marked as dead while rehashing
mm,vmscan: Make unregister_shrinker() no-op if register_shrinker() failed.
xfrm: Fix stack-out-of-bounds read on socket policy lookup.
xfrm: check id proto in validate_tmpl()
sctp: set frag_point in sctp_setsockopt_maxseg correctly
blktrace: fix unlocked registration of tracepoints
drm: Require __GFP_NOFAIL for the legacy drm_modeset_lock_all
ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE
Provide a function to create a NUL-terminated string from unterminated data
selinux: ensure the context is NUL terminated in security_context_to_sid_core()
selinux: skip bounded transition processing if the policy isn't loaded
crypto: x86/twofish-3way - Fix %rbp usage
staging: android: ion: Add __GFP_NOWARN for system contig heap
staging: android: ion: Switch from WARN to pr_warn
blk_rq_map_user_iov: fix error override
KVM: x86: fix escape of guest dr6 to the host
kcov: detect double association with a single task
netfilter: x_tables: fix int overflow in xt_alloc_table_info()
netfilter: x_tables: avoid out-of-bounds reads in xt_request_find_{match|target}
netfilter: ipt_CLUSTERIP: fix out-of-bounds accesses in clusterip_tg_check()
netfilter: on sockopt() acquire sock lock only in the required scope
netfilter: xt_cgroup: initialize info->priv in cgroup_mt_check_v1()
netfilter: xt_RATEEST: acquire xt_rateest_mutex for hash insert
rds: tcp: atomically purge entries from rds_tcp_conn_list during netns delete
net: avoid skb_warn_bad_offload on IS_ERR
crypto: hash - annotate algorithms taking optional key
crypto: hash - prevent using keyed hashes without setting key
ASoC: ux500: add MODULE_LICENSE tag
video: fbdev/mmp: add MODULE_LICENSE
ARM: 8743/1: bL_switcher: add MODULE_LICENSE tag
arm64: dts: add #cooling-cells to CPU nodes
dn_getsockoptdecnet: move nf_{get/set}sockopt outside sock lock
staging: android: ashmem: Fix a race condition in pin ioctls
binder: check for binder_thread allocation failure in binder_poll()
staging: iio: adc: ad7192: fix external frequency setting
staging: iio: ad5933: switch buffer mode to software
usbip: keep usbip_device sockfd state in sync with tcp_socket
usb: build drivers/usb/common/ when USB_SUPPORT is set
ARM: OMAP2+: Fix SRAM virt to phys translation for save_secure_ram_context
ARM: AM33xx: PRM: Remove am33xx_pwrdm_read_prev_pwrst function
ARM: dts: Fix omap4 hang with GPS connected to USB by using wakeupgen
ARM: dts: logicpd-som-lv: Fix gpmc addresses for NAND and enet
ARM: dts: logicpd-somlv: Fix wl127x pinmux
ARM: dts: am4372: Correct the interrupts_properties of McASP
ARM: dts: am437x-cm-t43: Correct the dmas property of spi0
perf top: Fix window dimensions change handling
perf bench numa: Fixup discontiguous/sparse numa nodes
media: s5k6aa: describe some function parameters
pinctrl: sunxi: Fix A80 interrupt pin bank
pinctrl: sunxi: Fix A64 UART mux value
i40iw: Correct ARP index mask
RDMA/cma: Make sure that PSN is not over max allowed
sctp: only update outstanding_bytes for transmitted queue when doing prsctp_prune
scripts/kernel-doc: Don't fail with status != 0 if error encountered with -none
ipvlan: Add the skb->mark as flow4's member to lookup route
m68k: add missing SOFTIRQENTRY_TEXT linker section
powerpc/perf: Fix oops when grouping different pmu events
s390/dasd: prevent prefix I/O error
ARM: dts: Fix elm interrupt compiler warning
gianfar: fix a flooded alignment reports because of padding issue.
net_sched: red: Avoid devision by zero
net_sched: red: Avoid illegal values
btrfs: Fix possible off-by-one in btrfs_search_path_in_tree
brcmfmac: Avoid build error with make W=1
net: ethernet: arc: fix error handling in emac_rockchip_probe
509: fix printing uninitialized stack memory when OID is empty
gianfar: Disable EEE autoneg by default
dmaengine: ioat: Fix error handling path
dmaengine: at_hdmac: fix potential NULL pointer dereference in atc_prep_dma_interleaved
clk: fix a panic error caused by accessing NULL pointer
ASoC: rockchip: disable clock on error
spi: sun4i: disable clocks in the remove function
xfrm: Fix stack-out-of-bounds with misconfigured transport mode policies.
drm/armada: fix leak of crtc structure
dmaengine: jz4740: disable/unprepare clk if probe fails
usb: dwc3: gadget: Wait longer for controller to end command processing
usb: dwc3: of-simple: fix missing clk_disable_unprepare
mm/early_ioremap: Fix boot hang with earlyprintk=efi,keep
x86/mm/kmmio: Fix mmiotrace for page unaligned addresses
platform/x86: dell-laptop: Fix keyboard max lighting for Dell Latitude E6410
xen: XEN_ACPI_PROCESSOR is Dom0-only
hippi: Fix a Fix a possible sleep-in-atomic bug in rr_close
powerpc/64s: Fix conversion of slb_miss_common to use RFI_TO_USER/KERNEL
powerpc/64s: Simple RFI macro conversions
powerpc/64s: Improve RFI L1-D cache flush fallback
crypto: talitos - fix Kernel Oops on hashing an empty file
drm/i915: fix intel_backlight_device_register declaration
shmem: avoid maybe-uninitialized warning
clk: sunxi-ng: fix build error without CONFIG_RESET_CONTROLLER
vmxnet3: prevent building with 64K pages
perf/x86: Shut up false-positive -Wmaybe-uninitialized warning
PCI: vmd: Fix suspend handlers defined-but-not-used warning
gpio: intel-mid: Fix build warning when !CONFIG_PM
platform/x86: intel_mid_thermal: Fix suspend handlers unused warning
usb: musb: fix compilation warning on unused function
PCI: Change pci_host_common_probe() visibility
perf: xgene: Include module.h
video: fbdev: via: remove possibly unused variables
scsi: advansys: fix build warning for PCI=n
x86/ras/inject: Make it depend on X86_LOCAL_APIC=y
gpio: xgene: mark PM functions as __maybe_unused
arm64: define BUG() instruction without CONFIG_BUG
x86/fpu/math-emu: Fix possible uninitialized variable use
tools build: Add tools tree support for 'make -s'
x86/build: Silence the build with "make -s"
thermal: fix INTEL_SOC_DTS_IOSF_CORE dependencies
x86: add MULTIUSER dependency for KVM
dmaengine: zx: fix build warning
x86/platform: Add PCI dependency for PUNIT_ATOM_DEBUG
x86/vm86: Fix unused variable warning if THP is disabled
scsi: advansys: fix uninitialized data access
arm64: Kconfig: select COMPAT_BINFMT_ELF only when BINFMT_ELF is set
ALSA: hda/ca0132 - fix possible NULL pointer use
reiserfs: avoid a -Wmaybe-uninitialized warning
cw1200: fix bogus maybe-uninitialized warning
security/keys: BIG_KEY requires CONFIG_CRYPTO
drm: exynos: mark pm functions as __maybe_unused
rbd: silence bogus -Wmaybe-uninitialized warning
drm/nouveau: hide gcc-4.9 -Wmaybe-uninitialized
Input: tca8418_keypad - hide gcc-4.9 -Wmaybe-uninitialized warning
KVM: add X86_LOCAL_APIC dependency
shmem: fix compilation warnings on unused functions
tc358743: fix register i2c_rd/wr functions
go7007: add MEDIA_CAMERA_SUPPORT dependency
em28xx: only use mt9v011 if camera support is enabled
tw5864: use dev_warn instead of WARN to shut up warning
ISDN: eicon: reduce stack size of sig_ind function
clk: meson: gxbb: fix build error without RESET_CONTROLLER
kasan: rework Kconfig settings
drm/i915: hide unused intel_panel_set_backlight function
arm64: sunxi: always enable reset controller
binfmt_elf: compat: avoid unused function warning
spi: bcm-qspi: shut up warning about cfi header inclusion
idle: i7300: add PCI dependency
arm64: fix warning about swapper_pg_dir overflow
usb: phy: msm add regulator dependency
x86/microcode/AMD: Change load_microcode_amd()'s param to bool to fix preemptibility bug
KVM: async_pf: Fix #DF due to inject "Page not Present" and "Page Ready" exceptions simultaneously
KVM: VMX: clean up declaration of VPID/EPT invalidation types
KVM: nVMX: invvpid handling improvements
crypto: s5p-sss - Fix kernel Oops in AES-ECB mode
Linux 4.9.84
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Since commit 49d200deaa ("debugfs: prevent access to removed files'
private data"), a debugfs file's file_operations methods get proxied
through lifetime aware wrappers.
However, only a certain subset of the file_operations members is supported
by debugfs and ->mmap isn't among them -- it appears to be NULL from the
VFS layer's perspective.
This behaviour breaks the /sys/kernel/debug/kcov file introduced
concurrently with commit 5c9a8750a6 ("kernel: add kcov code coverage").
Since that file never gets removed, there is no file removal race and thus,
a lifetime checking proxy isn't needed.
Avoid the proxying for /sys/kernel/debug/kcov by creating it via
debugfs_create_file_unsafe() rather than debugfs_create_file().
Fixes: 49d200deaa ("debugfs: prevent access to removed files' private data")
Fixes: 5c9a8750a6 ("kernel: add kcov code coverage")
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Kcov causes the compiler to add a call to __sanitizer_cov_trace_pc() in
every basic block. Ftrace patches in a call to _mcount() to each
function it has annotated.
Letting these mechanisms annotate each other is a bad thing. Break the
loop by adding 'notrace' to __sanitizer_cov_trace_pc() so that ftrace
won't try to patch this code.
This patch lets arm64 with KCOV and STACK_TRACER boot.
Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kcov provides code coverage collection for coverage-guided fuzzing
(randomized testing). Coverage-guided fuzzing is a testing technique
that uses coverage feedback to determine new interesting inputs to a
system. A notable user-space example is AFL
(http://lcamtuf.coredump.cx/afl/). However, this technique is not
widely used for kernel testing due to missing compiler and kernel
support.
kcov does not aim to collect as much coverage as possible. It aims to
collect more or less stable coverage that is function of syscall inputs.
To achieve this goal it does not collect coverage in soft/hard
interrupts and instrumentation of some inherently non-deterministic or
non-interesting parts of kernel is disbled (e.g. scheduler, locking).
Currently there is a single coverage collection mode (tracing), but the
API anticipates additional collection modes. Initially I also
implemented a second mode which exposes coverage in a fixed-size hash
table of counters (what Quentin used in his original patch). I've
dropped the second mode for simplicity.
This patch adds the necessary support on kernel side. The complimentary
compiler support was added in gcc revision 231296.
We've used this support to build syzkaller system call fuzzer, which has
found 90 kernel bugs in just 2 months:
https://github.com/google/syzkaller/wiki/Found-Bugs
We've also found 30+ bugs in our internal systems with syzkaller.
Another (yet unexplored) direction where kcov coverage would greatly
help is more traditional "blob mutation". For example, mounting a
random blob as a filesystem, or receiving a random blob over wire.
Why not gcov. Typical fuzzing loop looks as follows: (1) reset
coverage, (2) execute a bit of code, (3) collect coverage, repeat. A
typical coverage can be just a dozen of basic blocks (e.g. an invalid
input). In such context gcov becomes prohibitively expensive as
reset/collect coverage steps depend on total number of basic
blocks/edges in program (in case of kernel it is about 2M). Cost of
kcov depends only on number of executed basic blocks/edges. On top of
that, kernel requires per-thread coverage because there are always
background threads and unrelated processes that also produce coverage.
With inlined gcov instrumentation per-thread coverage is not possible.
kcov exposes kernel PCs and control flow to user-space which is
insecure. But debugfs should not be mapped as user accessible.
Based on a patch by Quentin Casasnovas.
[akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode']
[akpm@linux-foundation.org: unbreak allmodconfig]
[akpm@linux-foundation.org: follow x86 Makefile layout standards]
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Tavis Ormandy <taviso@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Kees Cook <keescook@google.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: David Drysdale <drysdale@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
