<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/fs/pstore/platform.c, branch v6.12.80</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v6.12.80</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v6.12.80'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2025-05-29T09:02:58+00:00</updated>
<entry>
<title>pstore: Change kmsg_bytes storage size to u32</title>
<updated>2025-05-29T09:02:58+00:00</updated>
<author>
<name>Kees Cook</name>
<email>kees@kernel.org</email>
</author>
<published>2025-02-06T19:16:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=16ddd67bb5579a14cb91c9692a11b1fd0349be45'/>
<id>urn:sha1:16ddd67bb5579a14cb91c9692a11b1fd0349be45</id>
<content type='text'>
[ Upstream commit 5674609535bafa834ab014d90d9bbe8e89223a0b ]

The types around kmsg_bytes were inconsistent. The global was unsigned
long, the argument to pstore_set_kmsg_bytes() was int, and the filesystem
option was u32. Given other internal limits, there's not much sense
in making a single pstore record larger than INT_MAX and it can't be
negative, so use u32 everywhere. Additionally, use READ/WRITE_ONCE and a
local variable in pstore_dump() to avoid kmsg_bytes changing during a
dump.

Link: https://lore.kernel.org/r/20250206191655.work.798-kees@kernel.org
Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'drm-next-2024-09-19' of https://gitlab.freedesktop.org/drm/kernel</title>
<updated>2024-09-19T08:18:15+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-09-19T08:18:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=de848da12f752170c2ebe114804a985314fd5a6a'/>
<id>urn:sha1:de848da12f752170c2ebe114804a985314fd5a6a</id>
<content type='text'>
Pull drm updates from Dave Airlie:
 "This adds a couple of patches outside the drm core, all should be
  acked appropriately, the string and pstore ones are the main ones that
  come to mind.

  Otherwise it's the usual drivers, xe is getting enabled by default on
  some new hardware, we've changed the device number handling to allow
  more devices, and we added some optional rust code to create QR codes
  in the panic handler, an idea first suggested I think 10 years ago :-)

  string:
   - add mem_is_zero()

  core:
   - support more device numbers
   - use XArray for minor ids
   - add backlight constants
   - Split dma fence array creation into alloc and arm

  fbdev:
   - remove usage of old fbdev hooks

  kms:
   - Add might_fault() to drm_modeset_lock priming
   - Add dynamic per-crtc vblank configuration support

  dma-buf:
   - docs cleanup

  buddy:
   - Add start address support for trim function

  printk:
   - pass description to kmsg_dump

  scheduler:
   - Remove full_recover from drm_sched_start

  ttm:
   - Make LRU walk restartable after dropping locks
   - Allow direct reclaim to allocate local memory

  panic:
   - add display QR code (in rust)

  displayport:
   - mst: GUID improvements

  bridge:
   - Silence error message on -EPROBE_DEFER
   - analogix: Clean aup
   - bridge-connector: Fix double free
   - lt6505: Disable interrupt when powered off
   - tc358767: Make default DP port preemphasis configurable
   - lt9611uxc: require DRM_BRIDGE_ATTACH_NO_CONNECTOR
   - anx7625: simplify OF array handling
   - dw-hdmi: simplify clock handling
   - lontium-lt8912b: fix mode validation
   - nwl-dsi: fix mode vsync/hsync polarity

  xe:
   - Enable LunarLake and Battlemage support
   - Introducing Xe2 ccs modifiers for integrated and discrete graphics
   - rename xe perf to xe observation
   - use wb caching on DGFX for system memory
   - add fence timeouts
   - Lunar Lake graphics/media/display workarounds
   - Battlemage workarounds
   - Battlemage GSC support
   - GSC and HuC fw updates for LL/BM
   - use dma_fence_chain_free
   - refactor hw engine lookup and mmio access
   - enable priority mem read for Xe2
   - Add first GuC BMG fw
   - fix dma-resv lock
   - Fix DGFX display suspend/resume
   - Use xe_managed for kernel BOs
   - Use reserved copy engine for user binds on faulting devices
   - Allow mixing dma-fence jobs and long-running faulting jobs
   - fix media TLB invalidation
   - fix rpm in TTM swapout path
   - track resources and VF state by PF

  i915:
   - Type-C programming fix for MTL+
   - FBC cleanup
   - Calc vblank delay more accurately
   - On DP MST, Enable LT fallback for UHBR&lt;-&gt;non-UHBR rates
   - Fix DP LTTPR detection
   - limit relocations to INT_MAX
   - fix long hangs in buddy allocator on DG2/A380

  amdgpu:
   - Per-queue reset support
   - SDMA devcoredump support
   - DCN 4.0.1 updates
   - GFX12/VCN4/JPEG4 updates
   - Convert vbios embedded EDID to drm_edid
   - GFX9.3/9.4 devcoredump support
   - process isolation framework for GFX 9.4.3/4
   - take IOMMU mappings into account for P2P DMA

  amdkfd:
   - CRIU fixes
   - HMM fix
   - Enable process isolation support for GFX 9.4.3/4
   - Allow users to target recommended SDMA engines
   - KFD support for targetting queues on recommended SDMA engines

  radeon:
   - remove .load and drm_dev_alloc
   - Fix vbios embedded EDID size handling
   - Convert vbios embedded EDID to drm_edid
   - Use GEM references instead of TTM
   - r100 cp init cleanup
   - Fix potential overflows in evergreen CS offset tracking

  msm:
   - DPU:
      - implement DP/PHY mapping on SC8180X
      - Enable writeback on SM8150, SC8180X, SM6125, SM6350
   - DP:
      - Enable widebus on all relevant chipsets
      - MSM8998 HDMI support
   - GPU:
      - A642L speedbin support
      - A615/A306/A621 support
      - A7xx devcoredump support

  ast:
   - astdp: Support AST2600 with VGA
   - Clean up HPD
   - Fix timeout loop for DP link training
   - reorganize output code by type (VGA, DP, etc)
   - convert to struct drm_edid
   - fix BMC handling for all outputs

  exynos:
   - drop stale MAINTAINERS pattern
   - constify struct

  loongson:
   - use GEM refcount over TTM

  mgag200:
   - Improve BMC handling
   - Support VBLANK intterupts
   - transparently support BMC outputs

  nouveau:
   - Refactor and clean up internals
   - Use GEM refcount over TTM's

  gm12u320:
   - convert to struct drm_edid

  gma500:
   - update i2c terms

  lcdif:
   - pixel clock fix

  host1x:
   - fix syncpoint IRQ during resume
   - use iommu_paging_domain_alloc()

  imx:
   - ipuv3: convert to struct drm_edid

  omapdrm:
   - improve error handling
   - use common helper for_each_endpoint_of_node()

  panel:
   - add support for BOE TV101WUM-LL2 plus DT bindings
   - novatek-nt35950: improve error handling
   - nv3051d: improve error handling
   - panel-edp:
      - add support for BOE NE140WUM-N6G
      - revert support for SDC ATNA45AF01
   - visionox-vtdr6130:
      - improve error handling
      - use devm_regulator_bulk_get_const()
   - boe-th101mb31ig002:
      - Support for starry-er88577 MIPI-DSI panel plus DT
      - Fix porch parameter
   - edp: Support AOU B116XTN02.3, AUO B116XAN06.1, AOU B116XAT04.1, BOE
     NV140WUM-N41, BOE NV133WUM-N63, BOE NV116WHM-A4D, CMN N116BCA-EA2,
     CMN N116BCP-EA2, CSW MNB601LS1-4
   - himax-hx8394: Support Microchip AC40T08A MIPI Display panel plus DT
   - ilitek-ili9806e: Support Densitron DMT028VGHMCMI-1D TFT plus DT
   - jd9365da:
      - Support Melfas lmfbx101117480 MIPI-DSI panel plus DT
      - Refactor for code sharing
   - panel-edp: fix name for HKC MB116AN01
   - jd9365da: fix "exit sleep" commands
   - jdi-fhd-r63452: simplify error handling with DSI multi-style
     helpers
   - mantix-mlaf057we51: simplify error handling with DSI multi-style
     helpers
   - simple:
      - support Innolux G070ACE-LH3 plus DT bindings
      - support On Tat Industrial Company KD50G21-40NT-A1 plus DT
        bindings
   - st7701:
      - decouple DSI and DRM code
      - add SPI support
      - support Anbernic RG28XX plus DT bindings

  mediatek:
   - support alpha blending
   - remove cl in struct cmdq_pkt
   - ovl adaptor fix
   - add power domain binding for mediatek DPI controller

  renesas:
   - rz-du: add support for RZ/G2UL plus DT bindings

  rockchip:
   - Improve DP sink-capability reporting
   - dw_hdmi: Support 4k@60Hz
   - vop:
      - Support RGB display on Rockchip RK3066
      - Support 4096px width

  sti:
   - convert to struct drm_edid

  stm:
   - Avoid UAF wih managed plane and CRTC helpers
   - Fix module owner
   - Fix error handling in probe
   - Depend on COMMON_CLK
   - ltdc:
      - Fix transparency after disabling plane
      - Remove unused interrupt

  tegra:
   - gr3d: improve PM domain handling
   - convert to struct drm_edid
   - Call drm_atomic_helper_shutdown()

  vc4:
   - fix PM during detect
   - replace DRM_ERROR() with drm_error()
   - v3d: simplify clock retrieval

  v3d:
   - Clean up perfmon

  virtio:
   - add DRM capset"

* tag 'drm-next-2024-09-19' of https://gitlab.freedesktop.org/drm/kernel: (1326 commits)
  drm/xe: Fix missing conversion to xe_display_pm_runtime_resume
  drm/xe/xe2hpg: Add Wa_15016589081
  drm/xe: Don't keep stale pointer to bo-&gt;ggtt_node
  drm/xe: fix missing 'xe_vm_put'
  drm/xe: fix build warning with CONFIG_PM=n
  drm/xe: Suppress missing outer rpm protection warning
  drm/xe: prevent potential UAF in pf_provision_vf_ggtt()
  drm/amd/display: Add all planes on CRTC to state for overlay cursor
  drm/i915/bios: fix printk format width
  drm/i915/display: Fix BMG CCS modifiers
  drm/amdgpu: get rid of bogus includes of fdtable.h
  drm/amdkfd: CRIU fixes
  drm/amdgpu: fix a race in kfd_mem_export_dmabuf()
  drm: new helper: drm_gem_prime_handle_to_dmabuf()
  drm/amdgpu/atomfirmware: Silence UBSAN warning
  drm/amdgpu: Fix kdoc entry in 'amdgpu_vm_cpu_prepare'
  drm/amd/amdgpu: apply command submission parser for JPEG v1
  drm/amd/amdgpu: apply command submission parser for JPEG v2+
  drm/amd/pm: fix the pp_dpm_pcie issue on smu v14.0.2/3
  drm/amd/pm: update the features set on smu v14.0.2/3
  ...
</content>
</entry>
<entry>
<title>pstore: replace spinlock_t by raw_spinlock_t</title>
<updated>2024-08-26T20:33:50+00:00</updated>
<author>
<name>Wen Yang</name>
<email>wen.yang@linux.dev</email>
</author>
<published>2024-08-19T14:59:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=1bf8012fc6997f2117f6919369cde16659db60e0'/>
<id>urn:sha1:1bf8012fc6997f2117f6919369cde16659db60e0</id>
<content type='text'>
pstore_dump() is called when both preemption and local IRQ are disabled,
and a spinlock is obtained, which is problematic for the RT kernel because
in this configuration, spinlocks are sleep locks.

Replace the spinlock_t with raw_spinlock_t to avoid sleeping in atomic context.

Signed-off-by: Wen Yang &lt;wen.yang@linux.dev&gt;
Cc: Kees Cook &lt;kees@kernel.org&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: Guilherme G. Piccoli &lt;gpiccoli@igalia.com&gt;
Cc: linux-hardening@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20240819145945.61274-1-wen.yang@linux.dev
Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'drm-misc-next-2024-08-01' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-next</title>
<updated>2024-08-08T16:58:46+00:00</updated>
<author>
<name>Daniel Vetter</name>
<email>daniel.vetter@ffwll.ch</email>
</author>
<published>2024-08-08T16:58:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=91dae758bdb854367bf0811d97acb84e791764d9'/>
<id>urn:sha1:91dae758bdb854367bf0811d97acb84e791764d9</id>
<content type='text'>
drm-misc-next for v6.12:

UAPI Changes:

virtio:
- Define DRM capset

Cross-subsystem Changes:

dma-buf:
- heaps: Clean up documentation

printk:
- Pass description to kmsg_dump()

Core Changes:

CI:
- Update IGT tests
- Point upstream repo to GitLab instance

modesetting:
- Introduce Power Saving Policy property for connectors
- Add might_fault() to drm_modeset_lock priming
- Add dynamic per-crtc vblank configuration support

panic:
- Avoid build-time interference with framebuffer console

docs:
- Document Colorspace property

scheduler:
- Remove full_recover from drm_sched_start

TTM:
- Make LRU walk restartable after dropping locks
- Allow direct reclaim to allocate local memory

Driver Changes:

amdgpu:
- Support Power Saving Policy connector property

ast:
- astdp: Support AST2600 with VGA; Clean up HPD

bridge:
- Silence error message on -EPROBE_DEFER
- analogix: Clean aup
- bridge-connector: Fix double free
- lt6505: Disable interrupt when powered off
- tc358767: Make default DP port preemphasis configurable

gma500:
- Update i2c terminology

ivpu:
- Add MODULE_FIRMWARE()

lcdif:
- Fix pixel clock

loongson:
- Use GEM refcount over TTM's

mgag200:
- Improve BMC handling
- Support VBLANK intterupts

nouveau:
- Refactor and clean up internals
- Use GEM refcount over TTM's

panel:
- Shutdown fixes plus documentation
- Refactor several drivers for better code sharing
- boe-th101mb31ig002: Support for starry-er88577 MIPI-DSI panel plus
  DT; Fix porch parameter
- edp: Support AOU B116XTN02.3, AUO B116XAN06.1, AOU B116XAT04.1,
  BOE NV140WUM-N41, BOE NV133WUM-N63, BOE NV116WHM-A4D, CMN N116BCA-EA2,
  CMN N116BCP-EA2, CSW MNB601LS1-4
- himax-hx8394: Support Microchip AC40T08A MIPI Display panel plus DT
- ilitek-ili9806e: Support Densitron DMT028VGHMCMI-1D TFT plus DT
- jd9365da: Support Melfas lmfbx101117480 MIPI-DSI panel plus DT; Refactor
  for code sharing

sti:
- Fix module owner

stm:
- Avoid UAF wih managed plane and CRTC helpers
- Fix module owner
- Fix error handling in probe
- Depend on COMMON_CLK
- ltdc: Fix transparency after disabling plane; Remove unused interrupt

tegra:
- Call drm_atomic_helper_shutdown()

v3d:
- Clean up perfmon

vkms:
- Clean up

Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
From: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20240801121406.GA102996@linux.fritz.box
</content>
</entry>
<entry>
<title>printk: Add a short description string to kmsg_dump()</title>
<updated>2024-07-17T10:35:24+00:00</updated>
<author>
<name>Jocelyn Falempe</name>
<email>jfalempe@redhat.com</email>
</author>
<published>2024-07-02T12:26:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=e1a261ba599eec97e1c5c7760d5c3698fc24e6a6'/>
<id>urn:sha1:e1a261ba599eec97e1c5c7760d5c3698fc24e6a6</id>
<content type='text'>
kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
callback.
This patch adds a new struct kmsg_dump_detail, that will hold the
reason and description, and pass it to the dump() callback.

To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
function and a macro for backward compatibility.

I've written this for drm_panic, but it can be useful for other
kmsg_dumper.
It allows to see the panic reason, like "sysrq triggered crash"
or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.

v2:
 * Use a struct kmsg_dump_detail to hold the reason and description
   pointer, for more flexibility if we want to add other parameters.
   (Kees Cook)
 * Fix powerpc/nvram_64 build, as I didn't update the forward
   declaration of oops_to_nvram()

Signed-off-by: Jocelyn Falempe &lt;jfalempe@redhat.com&gt;
Acked-by: Petr Mladek &lt;pmladek@suse.com&gt;
Acked-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt; (powerpc)
Acked-by: Kees Cook &lt;kees@kernel.org&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20240702122639.248110-1-jfalempe@redhat.com
</content>
</entry>
<entry>
<title>pstore: platform: add missing MODULE_DESCRIPTION() macro</title>
<updated>2024-06-17T18:56:12+00:00</updated>
<author>
<name>Jeff Johnson</name>
<email>quic_jjohnson@quicinc.com</email>
</author>
<published>2024-06-14T04:39:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=9b3c13c9ea4ecb2b95948f666560b8df8f358b40'/>
<id>urn:sha1:9b3c13c9ea4ecb2b95948f666560b8df8f358b40</id>
<content type='text'>
With ARCH=csky, make allmodconfig &amp;&amp; make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in fs/pstore/pstore.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson &lt;quic_jjohnson@quicinc.com&gt;
Link: https://lore.kernel.org/r/20240613-md-csky-fs-pstore-v1-1-c525f636b1cb@quicinc.com
Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
</content>
</entry>
<entry>
<title>pstore/platform: Add check for kstrdup</title>
<updated>2023-10-12T16:47:01+00:00</updated>
<author>
<name>Jiasheng Jiang</name>
<email>jiasheng@iscas.ac.cn</email>
</author>
<published>2023-06-23T02:27:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=a19d48f7c5d57c0f0405a7d4334d1d38fe9d3c1c'/>
<id>urn:sha1:a19d48f7c5d57c0f0405a7d4334d1d38fe9d3c1c</id>
<content type='text'>
Add check for the return value of kstrdup() and return the error
if it fails in order to avoid NULL pointer dereference.

Fixes: 563ca40ddf40 ("pstore/platform: Switch pstore_info::name to const")
Signed-off-by: Jiasheng Jiang &lt;jiasheng@iscas.ac.cn&gt;
Link: https://lore.kernel.org/r/20230623022706.32125-1-jiasheng@iscas.ac.cn
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
</content>
</entry>
<entry>
<title>pstore: Base compression input buffer size on estimated compressed size</title>
<updated>2023-08-31T20:58:49+00:00</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ardb@kernel.org</email>
</author>
<published>2023-08-30T21:22:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=94160062396d7e7cff4ed69320ffc5e22d51a0ab'/>
<id>urn:sha1:94160062396d7e7cff4ed69320ffc5e22d51a0ab</id>
<content type='text'>
Commit 1756ddea6916 ("pstore: Remove worst-case compression size logic")
removed some clunky per-algorithm worst case size estimation routines on
the basis that we can always store pstore records uncompressed, and
these worst case estimations are about how much the size might
inadvertently *increase* due to encapsulation overhead when the input
cannot be compressed at all. So if compression results in a size
increase, we just store the original data instead.

However, it seems that the original code was misinterpreting these
calculations as an estimation of how much uncompressed data might fit
into a compressed buffer of a given size, and it was using the results
to consume the input data in larger chunks than the pstore record size,
relying on the compression to ensure that what ultimately gets stored
fits into the available space.

One result of this, as observed and reported by Linus, is that upgrading
to a newer kernel that includes the given commit may result in pstore
decompression errors reported in the kernel log. This is due to the fact
that the existing records may unexpectedly decompress to a size that is
larger than the pstore record size.

Another potential problem caused by this change is that we may
underutilize the fixed sized records on pstore backends such as ramoops.
And on pstore backends with variable sized records such as EFI, we will
end up creating many more entries than before to store the same amount
of compressed data.

So let's fix both issues, by bringing back the typical case estimation of
how much ASCII text captured from the dmesg log might fit into a pstore
record of a given size after compression. The original implementation
used the computation given below for zlib:

  switch (size) {
  /* buffer range for efivars */
  case 1000 ... 2000:
  	cmpr = 56;
  	break;
  case 2001 ... 3000:
  	cmpr = 54;
  	break;
  case 3001 ... 3999:
  	cmpr = 52;
  	break;
  /* buffer range for nvram, erst */
  case 4000 ... 10000:
  	cmpr = 45;
  	break;
  default:
  	cmpr = 60;
  	break;
  }

  return (size * 100) / cmpr;

We will use the previous worst-case of 60% for compression. For
decompression go extra large (3x) so we make sure there's enough space
for anything.

While at it, rate limit the error message so we don't flood the log
unnecessarily on systems that have accumulated a lot of pstore history.

Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Eric Biggers &lt;ebiggers@kernel.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Herbert Xu &lt;herbert@gondor.apana.org.au&gt;
Signed-off-by: Ard Biesheuvel &lt;ardb@kernel.org&gt;
Link: https://lore.kernel.org/r/20230830212238.135900-1-ardb@kernel.org
Co-developed-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
</content>
</entry>
<entry>
<title>pstore: Support record sizes larger than kmalloc() limit</title>
<updated>2023-08-17T22:18:24+00:00</updated>
<author>
<name>Yuxiao Zhang</name>
<email>yuxiaozhang@google.com</email>
</author>
<published>2023-06-27T20:25:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=104fd0b5e948157f8e8ac88a20b46ba8641d4e95'/>
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Currently pstore record buffers are allocated using kmalloc() which has
a maximum size based on page size. If a large "pmsg-size" module
parameter is specified, pmsg will fail to copy the contents since
memdup_user() is limited to kmalloc() allocation sizes.

Since we don't need physically contiguous memory for any of the pstore
record buffers, use kvzalloc() to avoid such limitations in the core of
pstore and in the ram backend, and explicitly read from userspace using
vmemdup_user(). This also means that any other backends that want to
(or do already) support larger record sizes will Just Work now.

Signed-off-by: Yuxiao Zhang &lt;yuxiaozhang@google.com&gt;
Link: https://lore.kernel.org/r/20230627202540.881909-2-yuxiaozhang@google.com
Co-developed-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
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</entry>
<entry>
<title>pstore: Replace crypto API compression with zlib_deflate library calls</title>
<updated>2023-07-17T23:08:58+00:00</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ardb@kernel.org</email>
</author>
<published>2023-07-12T16:23:32+00:00</published>
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Pstore supports compression using a variety of algorithms exposed by the
crypto API. This uses the deprecated comp (as opposed to scomp/acomp)
API, and so we should stop using that, and either move to the new API,
or switch to a different approach entirely.

Given that we only compress ASCII text in pstore, and considering that
this happens when the system is likely to be in an unstable state, the
flexibility that the complex crypto API provides does not outweigh its
impact on the risk that we might encounter additional problems when
trying to commit the kernel log contents to the pstore backend.

So let's switch [back] to the zlib deflate library API, and remove all
the complexity that really has no place in a low-level diagnostic
facility. Note that, while more modern compression algorithms have been
added to the kernel in recent years, the code size of zlib deflate is
substantially smaller than, e.g., zstd, while its performance in terms
of compression ratio is comparable for ASCII text, and speed is deemed
irrelevant in this context.

Note that this means that compressed pstore records may no longer be
accessible after a kernel upgrade, but this has never been part of the
contract. (The choice of compression algorithm is not stored in the
pstore records either)

Tested-by: "Guilherme G. Piccoli" &lt;gpiccoli@igalia.com&gt; # Steam Deck
Signed-off-by: Ard Biesheuvel &lt;ardb@kernel.org&gt;
Reviewed-by: Eric Biggers &lt;ebiggers@google.com&gt;
Link: https://lore.kernel.org/r/20230712162332.2670437-3-ardb@kernel.org
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
</content>
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