[Why]
Getting below errors:
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:1414:5: error: implicit conversion from enumeration type 'enum scan_direction_class' to different enumeration type 'enum dm_rotation_angle' [-Werror,-Wenum-conversion]
mode_lib->vba.SourceScan[k],
^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:1744:22: error: implicit conversion from enumeration type 'enum scan_direction_class' to different enumeration type 'enum dm_rotation_angle' [-Werror,-Wenum-conversion]
&& (!(!IsVertical(mode_lib->vba.SourceScan[k])) || mode_lib->vba.DCCEnable[k] == true)) {
~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~
2 errors generated.
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_util_32.c:5484:18: error: implicit conversion from enumeration type 'RequestType' to different enumeration type 'enum RequestType' [-Werror,-Wenum-conversion]
RequestLuma = REQ_256Bytes;
~ ^~~~~~~~~~~~
18 errors of similar kind
[How]
1. Add typecast at relevant places
2. Move the enum RequestType definition ahead of declarations
Signed-off-by: Chandan Vurdigere Nataraj <chandan.vurdigerenataraj@amd.com>
Reviewed-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
After the commit ca522482e3 ("dm: pass NULL bdev to bio_alloc_clone"),
clone_endio() only calls dm_zone_endio() when DM targets remap the
clone bio's bdev to something other than the md->disk->part0 default.
However, if a DM target (e.g. dm-crypt) stacked ontop of a dm-zoned
does not remap the clone bio using bio_set_dev() then dm_zone_endio()
is not called at completion of the bios and zone locks are not
properly unlocked. This triggers a hang, in dm_zone_map_bio(), when
blktests block/004 is run for dm-crypt on zoned block devices. To
avoid the hang, simply remove the clone_endio() check that verifies
the target remapped the clone bio to a device other than the default.
Fixes: ca522482e3 ("dm: pass NULL bdev to bio_alloc_clone")
Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Pull power management fixes from Rafael Wysocki:
"These fix an intel_idle issue introduced during the 5.16 development
cycle and two recent regressions in the system reboot/poweroff code.
Specifics:
- Fix CPUIDLE_FLAG_IRQ_ENABLE handling in intel_idle (Peter Zijlstra)
- Allow all platforms to use the global poweroff handler and make
non-syscall poweroff code paths work again (Dmitry Osipenko)"
* tag 'pm-5.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE
kernel/reboot: Fix powering off using a non-syscall code paths
kernel/reboot: Use static handler for register_platform_power_off()
As Liviu pointed out, the arm,malidp-arqos-high-level property
mentioned in the original .txt binding was a mistake, and
arm,malidp-arqos-value needs to take its place.
The binding commit ce6eb0253c ("dt/bindings: display: Add optional
property node define for Mali DP500") mentions the right name in the
commit message, but has the wrong name in the diff.
Commit d298e6a27a ("drm/arm/mali-dp: Add display QoS interface
configuration for Mali DP500") uses the property in the driver, but uses
the shorter name.
Remove the wrong property from the binding, and use the proper name in
the example. The actual property was already documented properly.
Fixes: 2c8b082a3a ("dt-bindings: display: convert Arm Mali-DP to DT schema")
Link: https://lore.kernel.org/linux-arm-kernel/YnumGEilUblhBx8E@e110455-lin.cambridge.arm.com/
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reported-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220609162729.1441760-1-andre.przywara@arm.com
Merge fixes for regressions introduced by the recent rework of the
system reboot/poweroff code.
* pm-sysoff:
kernel/reboot: Fix powering off using a non-syscall code paths
kernel/reboot: Use static handler for register_platform_power_off()
Pull documentation fixes from Jonathan Corbet:
"A few documentation fixes for 5.19, including moving the new HTE docs
to a more suitable location, adding loongarch to the features lists,
and a couple of typo fixes"
* tag 'docs-5.19-3' of git://git.lwn.net/linux:
docs: arm: tcm: Fix typo in description of TCM and MMU usage
docs: Move the HTE documentation to driver-api/
docs: usb: fix literal block marker in usbmon verification example
Documentation/features: Update the arch support status files
Pull arm64 fixes from Catalin Marinas:
- SME save/restore for EFI fix - incorrect logic for detecting the need
for saving/restoring the FFR state.
- SME fix for a CPU ID field value.
- Sysreg generation awk script fix (comparison operator).
- Some typos in documentation or comments and silence a sparse warning
(missing prototype).
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: Add kasan_hw_tags_enable() prototype to silence sparse
arm64/sme: Fix EFI save/restore
arm64/fpsimd: Fix typo in comment
arm64/sysreg: Fix typo in Enum element regex
arm64/sme: Fix SVE/SME typo in ABI documentation
arm64/sme: Fix tests for 0b1111 value ID registers
Pull zonefs fixes from Damien Le Moal:
- Fix handling of the explicit-open mount option, and in particular the
conditions under which this option can be ignored.
- Fix a problem with zonefs iomap_begin method, causing a hang in
iomap_readahead() when a readahead request reaches the end of a file.
* tag 'zonefs-5.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/zonefs:
zonefs: fix zonefs_iomap_begin() for reads
zonefs: Do not ignore explicit_open with active zone limit
zonefs: fix handling of explicit_open option on mount
Pull ATA fixes from Damien Le Moal:
"Several small fixes for rc2:
- Remove unused field in struct ata_port (Hannes)
- Fix a potential (very unlikely) NULL pointer dereference in
ata_host_alloc_pinfo() (Sergey)
- Fix a device reference leak in the pata_octeon_cf driver (Miaoqian)
- Fixes for handling access to the concurrent positioning ranges log
page used with multi-actuator HDDs (Tyler)
- Fix the values shown by the pio_mode and dma_mode sysfs device
attributes (Sergey)
- Update the MAINTAINERS file to add libata sysfs ABI documentation
file (Sergey)"
* tag 'ata-5.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata:
MAINTAINERS: add ATA sysfs file documentation to libata entry
ata: libata-transport: fix {dma|pio|xfer}_mode sysfs files
libata: fix translation of concurrent positioning ranges
libata: fix reading concurrent positioning ranges log
ata: pata_octeon_cf: Fix refcount leak in octeon_cf_probe
ata: libata-core: fix NULL pointer deref in ata_host_alloc_pinfo()
ata: libata: drop 'sas_last_tag'
Pull sound fixes from Takashi Iwai:
"A collection of fixes; almost all changes are device-specific small
fixes over ASoC, HD-audio and USB-audio. No sign of serious breakage,
so far"
* tag 'sound-5.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (23 commits)
ALSA: hda/realtek: Add quirk for HP Dev One
ALSA: hda/realtek - Add HW8326 support
ALSA: hda/conexant - Fix loopback issue with CX20632
ALSA: hda: MTL: add HD Audio PCI ID and HDMI codec vendor ID
ALSA: usb-audio: Set up (implicit) sync for Saffire 6
ALSA: usb-audio: Skip generic sync EP parse for secondary EP
ASoC: wm_adsp: Fix event generation for wm_adsp_fw_put()
ASoC: es8328: Fix event generation for deemphasis control
ASoC: wm8962: Fix suspend while playing music
ASoC: SOF: ipc-msg-injector: Fix reversed if statement
ASoC: SOF: ipc-msg-injector: Propagate write errors correctly
ASoC: fsl_sai: Add support for i.MX8MN
ASoC: SOF: Fix potential NULL pointer dereference
ALSA: hda/realtek: Fix for quirk to enable speaker output on the Lenovo Yoga DuetITL 2021
ASoC: cs42l51: Correct minimum value for SX volume control
ASoC: cs42l56: Correct typo in minimum level for SX volume controls
ASoC: cs42l52: Correct TLV for Bypass Volume
ASoC: cs53l30: Correct number of volume levels on SX controls
ASoC: cs35l36: Update digital volume TLV
ASoC: cs42l52: Fix TLV scales for mixer controls
...
Pull drm fixes from Dave Airlie:
"Not a huge amount here, mainly a bunch of scattered amdgpu fixes, and
then some misc panfrost, bridge/panel ones, and one ast fix for
multi-monitors. Probably pick up a bit more next week like rc3 often
does.
amdgpu:
- DCN 3.1 golden settings fix
- eDP fixes
- DMCUB fixes
- GFX11 fixes and cleanups
- VCN fix for yellow carp
- GMC11 fixes
- RAS fixes
- GPUVM TLB flush fixes
- SMU13 fixes
- VCN3 AV1 regression fix
- VCN2 JPEG fix
- Other misc fixes
amdkfd:
- MMU notifier fix
- Support for more GC 10.3.x families
- Pinned BO handling fix
- Partial migration bug fix
panfrost:
- fix a use after free
ti-sn65dsi83:
- fix invalid DT configuration
panel:
- two self refresh fixes
ast:
- multiple output fix"
* tag 'drm-fixes-2022-06-10' of git://anongit.freedesktop.org/drm/drm: (37 commits)
drm/ast: Support multiple outputs
drm/amdgpu/mes: only invalid/prime icache when finish loading both pipe MES FWs.
drm/amdgpu/jpeg2: Add jpeg vmid update under IB submit
drm/amdgpu: always flush the TLB on gfx8
drm/amdgpu: fix limiting AV1 to the first instance on VCN3
drm/amdkfd:Fix fw version for 10.3.6
drm/amdgpu: Add MODE register to wave debug info in gfx11
Revert "drm/amd/display: Pass the new context into disable OTG WA"
Revert "drm/amdgpu: Ensure the DMA engine is deactivated during set ups"
drm/atomic: Force bridge self-refresh-exit on CRTC switch
drm/bridge: analogix_dp: Support PSR-exit to disable transition
drm/amdgpu: suppress the compile warning about 64 bit type
drm/amd/pm: suppress compile warnings about possible unaligned accesses
drm/amdkfd: Fix partial migration bugs
drm/amdkfd: add pinned BOs to kfd_bo_list
drm/amdgpu: Update PDEs flush TLB if PTB/PDB moved
drm/amdgpu: enable tmz by default for GC 10.3.7
drm/amdkfd: Add GC 10.3.6 and 10.3.7 KFD definitions
drm/amdkfd: Use mmget_not_zero in MMU notifier
drm/amdgpu: Resolve RAS GFX error count issue after cold boot on Arcturus
...
Pull networking fixes from Jakub Kicinski:
"Quick follow up, to cleanly fast-forward net again.
Current release - new code bugs:
- Revert "net/mlx5e: Allow relaxed ordering over VFs"
Previous releases - regressions:
- seg6: fix seg6_lookup_any_nexthop() to handle VRFs using
flowi_l3mdev
Misc:
- rename TLS_INFO_ZC_SENDFILE to better express the meaning"
* tag 'net-5.19-rc2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net:
net: seg6: fix seg6_lookup_any_nexthop() to handle VRFs using flowi_l3mdev
nfp: flower: restructure flow-key for gre+vlan combination
nfp: avoid unnecessary check warnings in nfp_app_get_vf_config
tls: Rename TLS_INFO_ZC_SENDFILE to TLS_INFO_ZC_TX
net/mlx5: fs, fail conflicting actions
net/mlx5: Rearm the FW tracer after each tracer event
net/mlx5: E-Switch, pair only capable devices
net/mlx5e: CT: Fix cleanup of CT before cleanup of TC ct rules
Revert "net/mlx5e: Allow relaxed ordering over VFs"
MAINTAINERS: adjust MELLANOX ETHERNET INNOVA DRIVERS to TLS support removal
This function is only called from assembly, no need for a prototype
declaration in a header file. In addition, add #ifdef around the
function since it is only used when CONFIG_KASAN_HW_TAGS.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: kernel test robot <lkp@intel.com>
Pull xen updates from Juergen Gross:
- a small cleanup removing "export" of an __init function
- a small series adding a new infrastructure for platform flags
- a series adding generic virtio support for Xen guests (frontend side)
* tag 'for-linus-5.19a-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: unexport __init-annotated xen_xlate_map_ballooned_pages()
arm/xen: Assign xen-grant DMA ops for xen-grant DMA devices
xen/grant-dma-ops: Retrieve the ID of backend's domain for DT devices
xen/grant-dma-iommu: Introduce stub IOMMU driver
dt-bindings: Add xen,grant-dma IOMMU description for xen-grant DMA ops
xen/virtio: Enable restricted memory access using Xen grant mappings
xen/grant-dma-ops: Add option to restrict memory access under Xen
xen/grants: support allocating consecutive grants
arm/xen: Introduce xen_setup_dma_ops()
virtio: replace arch_has_restricted_virtio_memory_access()
kernel: add platform_has() infrastructure
Commit b260fccaeb ("firmware: arm_scmi: Add SCMI v3.1 protocol extended
names support") moved all the name string buffers to use the extended buffer
size of 64 instead of the required 16 bytes. While that should be fine if
the firmware terminates the string before 16 bytes, there is possibility
of copying random data if the name is not NULL terminated by the firmware.
SCMI base protocol agent_name/vendor_id/sub_vendor_id are defined by the
specification as NULL-terminated ASCII strings up to 16-bytes in length.
The underlying buffers and message descriptors are currently bigger than
needed; resize them to fit only the strictly needed 16 bytes to avoid
any possible leaks when reading data from the firmware.
Change the size argument of strlcpy to use SCMI_SHORT_NAME_MAX_SIZE always
when dealing with short domain names, so as to limit the possibility that
an ill-formed non-NULL terminated short reply from the SCMI platform
firmware can leak stale content laying in the underlying transport shared
memory area.
While at that, convert all strings handling routines to use the preferred
strscpy.
Link: https://lore.kernel.org/r/20220608095530.497879-1-cristian.marussi@arm.com
Fixes: b260fccaeb ("firmware: arm_scmi: Add SCMI v3.1 protocol extended names support")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Pull MIPS fix from Thomas Bogendoerfer:
"Build fix for Loongson-3"
* tag 'mips-fixes_5.19_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
MIPS: Loongson-3: fix compile mips cpu_hwmon as module build error.
When a write command to a sequential write required or sequential write
preferred zone result in the zone write pointer reaching the end of the
zone, the zone condition must be set to full AND the number of implicitly
or explicitly open zones updated to have a correct accounting for zone
resources. However, the function zbc_inc_wp() only sets the zone condition
to full without updating the open zone counters, resulting in a zone state
machine breakage.
Introduce the helper function zbc_set_zone_full() and use it in
zbc_inc_wp() to correctly transition zones to the full condition.
Link: https://lore.kernel.org/r/20220608011302.92061-1-damien.lemoal@opensource.wdc.com
Fixes: f0d1cf9378 ("scsi: scsi_debug: Add ZBC zone commands")
Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The EFI save/restore code is confused. When saving the check for saving
FFR is inverted due to confusion with the streaming mode check, and when
restoring we check if we need to restore FFR by checking the percpu
efi_sm_state without the required wrapper rather than based on the
combination of FA64 support and streaming mode.
Fixes: e0838f6373 ("arm64/sme: Save and restore streaming mode over EFI runtime calls")
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220602124132.3528951-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
In fsl_mc_bus_remove(), mc->root_mc_bus_dev->mc_io is passed to
fsl_destroy_mc_io(). However, mc->root_mc_bus_dev is already freed in
fsl_mc_device_remove(). Then reference to mc->root_mc_bus_dev->mc_io
triggers KASAN use-after-free. To avoid the use-after-free, keep the
reference to mc->root_mc_bus_dev->mc_io in a local variable and pass to
fsl_destroy_mc_io().
This patch needs rework to apply to kernels older than v5.15.
Fixes: f93627146f ("staging: fsl-mc: fix asymmetry in destroy of mc_io")
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20220601105159.87752-1-shinichiro.kawasaki@wdc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Clang warns:
drivers/misc/cardreader/rts5261.c:406:13: error: variable 'setting_reg2' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
} else if (efuse_valid == 0) {
^~~~~~~~~~~~~~~~
drivers/misc/cardreader/rts5261.c:412:30: note: uninitialized use occurs here
pci_read_config_dword(pdev, setting_reg2, &lval2);
^~~~~~~~~~~~
efuse_valid == 1 is not a valid value so just return early from the
function to avoid using setting_reg2 uninitialized.
Fixes: b1c5f30851 ("misc: rtsx: add rts5261 efuse function")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Tom Rix <trix@redhat.com>
Suggested-by: Ricky WU <ricky_wu@realtek.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20220523150521.2947108-1-nathan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently if the APB or Debounce clocks aren't yet ready to be requested
the DW GPIO driver will correctly handle that by deferring the probe
procedure, but the error is still printed to the system log. It needlessly
pollutes the log since there was no real error but a request to postpone
the clock request procedure since the clocks subsystem hasn't been fully
initialized yet. Let's fix that by using the dev_err_probe method to print
the APB/clock request error status. It will correctly handle the deferred
probe situation and print the error if it actually happens.
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Pass the correct dev_id to free_irq() to fix this splat when the driver
is unbound:
WARNING: CPU: 0 PID: 30 at kernel/irq/manage.c:1895 free_irq
Trying to free already-free IRQ 65
Call Trace:
warn_slowpath_fmt
free_irq
goldfish_tty_remove
platform_remove
device_remove
device_release_driver_internal
device_driver_detach
unbind_store
drv_attr_store
...
Fixes: 465893e188 ("tty: goldfish: support platform_device with id -1")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20220609141704.1080024-1-vincent.whitchurch@axis.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In suspend sequence there is a need to perform stop_rx during suspend
sequence to prevent any asynchronous data over rx line. However this
can cause problem to drivers which dont do re-start_rx during set_termios.
Add new callback start_rx and perform stop_rx only when implementation of
start_rx is present. Also add call to start_rx in resume sequence so that
drivers who come across this problem can make use of this framework.
Fixes: c9d2325cdb ("serial: core: Do stop_rx in suspend path for console if console_suspend is disabled")
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
Link: https://lore.kernel.org/r/1654627965-1461-2-git-send-email-quic_vnivarth@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
With arch randomness being used by every distro and enabled in
defconfigs, the distinction between rng_has_arch_random() and
rng_is_initialized() is now rather small. In fact, the places where they
differ are now places where paranoid users and system builders really
don't want arch randomness to be used, in which case we should respect
that choice, or places where arch randomness is known to be broken, in
which case that choice is all the more important. So this commit just
removes the function and its one user.
Reviewed-by: Petr Mladek <pmladek@suse.com> # for vsprintf.c
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit changes the default Kconfig values of RANDOM_TRUST_CPU and
RANDOM_TRUST_BOOTLOADER to be Y by default. It does not change any
existing configs or change any kernel behavior. The reason for this is
several fold.
As background, I recently had an email thread with the kernel
maintainers of Fedora/RHEL, Debian, Ubuntu, Gentoo, Arch, NixOS, Alpine,
SUSE, and Void as recipients. I noted that some distros trust RDRAND,
some trust EFI, and some trust both, and I asked why or why not. There
wasn't really much of a "debate" but rather an interesting discussion of
what the historical reasons have been for this, and it came up that some
distros just missed the introduction of the bootloader Kconfig knob,
while another didn't want to enable it until there was a boot time
switch to turn it off for more concerned users (which has since been
added). The result of the rather uneventful discussion is that every
major Linux distro enables these two options by default.
While I didn't have really too strong of an opinion going into this
thread -- and I mostly wanted to learn what the distros' thinking was
one way or another -- ultimately I think their choice was a decent
enough one for a default option (which can be disabled at boot time).
I'll try to summarize the pros and cons:
Pros:
- The RNG machinery gets initialized super quickly, and there's no
messing around with subsequent blocking behavior.
- The bootloader mechanism is used by kexec in order for the prior
kernel to initialize the RNG of the next kernel, which increases
the entropy available to early boot daemons of the next kernel.
- Previous objections related to backdoors centered around
Dual_EC_DRBG-like kleptographic systems, in which observing some
amount of the output stream enables an adversary holding the right key
to determine the entire output stream.
This used to be a partially justified concern, because RDRAND output
was mixed into the output stream in varying ways, some of which may
have lacked pre-image resistance (e.g. XOR or an LFSR).
But this is no longer the case. Now, all usage of RDRAND and
bootloader seeds go through a cryptographic hash function. This means
that the CPU would have to compute a hash pre-image, which is not
considered to be feasible (otherwise the hash function would be
terribly broken).
- More generally, if the CPU is backdoored, the RNG is probably not the
realistic vector of choice for an attacker.
- These CPU or bootloader seeds are far from being the only source of
entropy. Rather, there is generally a pretty huge amount of entropy,
not all of which is credited, especially on CPUs that support
instructions like RDRAND. In other words, assuming RDRAND outputs all
zeros, an attacker would *still* have to accurately model every single
other entropy source also in use.
- The RNG now reseeds itself quite rapidly during boot, starting at 2
seconds, then 4, then 8, then 16, and so forth, so that other sources
of entropy get used without much delay.
- Paranoid users can set random.trust_{cpu,bootloader}=no in the kernel
command line, and paranoid system builders can set the Kconfig options
to N, so there's no reduction or restriction of optionality.
- It's a practical default.
- All the distros have it set this way. Microsoft and Apple trust it
too. Bandwagon.
Cons:
- RDRAND *could* still be backdoored with something like a fixed key or
limited space serial number seed or another indexable scheme like
that. (However, it's hard to imagine threat models where the CPU is
backdoored like this, yet people are still okay making *any*
computations with it or connecting it to networks, etc.)
- RDRAND *could* be defective, rather than backdoored, and produce
garbage that is in one way or another insufficient for crypto.
- Suggesting a *reduction* in paranoia, as this commit effectively does,
may cause some to question my personal integrity as a "security
person".
- Bootloader seeds and RDRAND are generally very difficult if not all
together impossible to audit.
Keep in mind that this doesn't actually change any behavior. This
is just a change in the default Kconfig value. The distros already are
shipping kernels that set things this way.
Ard made an additional argument in [1]:
We're at the mercy of firmware and micro-architecture anyway, given
that we are also relying on it to ensure that every instruction in
the kernel's executable image has been faithfully copied to memory,
and that the CPU implements those instructions as documented. So I
don't think firmware or ISA bugs related to RNGs deserve special
treatment - if they are broken, we should quirk around them like we
usually do. So enabling these by default is a step in the right
direction IMHO.
In [2], Phil pointed out that having this disabled masked a bug that CI
otherwise would have caught:
A clean 5.15.45 boots cleanly, whereas a downstream kernel shows the
static key warning (but it does go on to boot). The significant
difference is that our defconfigs set CONFIG_RANDOM_TRUST_BOOTLOADER=y
defining that on top of multi_v7_defconfig demonstrates the issue on
a clean 5.15.45. Conversely, not setting that option in a
downstream kernel build avoids the warning
[1] https://lore.kernel.org/lkml/CAMj1kXGi+ieviFjXv9zQBSaGyyzeGW_VpMpTLJK8PJb2QHEQ-w@mail.gmail.com/
[2] https://lore.kernel.org/lkml/c47c42e3-1d56-5859-a6ad-976a1a3381c6@raspberrypi.com/
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
