CVE-2021-47497
Assigner: Linux
Published: 2024-05-22T08:19:44.144Z
State: PUBLISHED
descriptions: value: In the Linux kernel, the following vulnerability has been resolved:

nvmem: Fix shift-out-of-bound (UBSAN) with byte size cells

If a cell has 'nbits' equal to a multiple of BITS_PER_BYTE the logic

 *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);

will become undefined behavior because nbits modulo BITS_PER_BYTE is 0, and we
subtract one from that making a large number that is then shifted more than the
number of bits that fit into an unsigned long.

UBSAN reports this problem:

 UBSAN: shift-out-of-bounds in drivers/nvmem/core.c:1386:8
 shift exponent 64 is too large for 64-bit type 'unsigned long'
 CPU: 6 PID: 7 Comm: kworker/u16:0 Not tainted 5.15.0-rc3+ #9
 Hardware name: Google Lazor (rev3+) with KB Backlight (DT)
 Workqueue: events_unbound deferred_probe_work_func
 Call trace:
  dump_backtrace+0x0/0x170
  show_stack+0x24/0x30
  dump_stack_lvl+0x64/0x7c
  dump_stack+0x18/0x38
  ubsan_epilogue+0x10/0x54
  __ubsan_handle_shift_out_of_bounds+0x180/0x194
  __nvmem_cell_read+0x1ec/0x21c
  nvmem_cell_read+0x58/0x94
  nvmem_cell_read_variable_common+0x4c/0xb0
  nvmem_cell_read_variable_le_u32+0x40/0x100
  a6xx_gpu_init+0x170/0x2f4
  adreno_bind+0x174/0x284
  component_bind_all+0xf0/0x264
  msm_drm_bind+0x1d8/0x7a0
  try_to_bring_up_master+0x164/0x1ac
  __component_add+0xbc/0x13c
  component_add+0x20/0x2c
  dp_display_probe+0x340/0x384
  platform_probe+0xc0/0x100
  really_probe+0x110/0x304
  __driver_probe_device+0xb8/0x120
  driver_probe_device+0x4c/0xfc
  __device_attach_driver+0xb0/0x128
  bus_for_each_drv+0x90/0xdc
  __device_attach+0xc8/0x174
  device_initial_probe+0x20/0x2c
  bus_probe_device+0x40/0xa4
  deferred_probe_work_func+0x7c/0xb8
  process_one_work+0x128/0x21c
  process_scheduled_works+0x40/0x54
  worker_thread+0x1ec/0x2a8
  kthread+0x138/0x158
  ret_from_fork+0x10/0x20

Fix it by making sure there are any bits to mask out.
affected: product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions: version: 69aba7948cbe
lessThan: abcb8d33e4d2
status: affected
versionType: git
version: 69aba7948cbe
lessThan: 60df06bbdf49
status: affected
versionType: git
version: 69aba7948cbe
lessThan: 2df6c0230502
status: affected
versionType: git
version: 69aba7948cbe
lessThan: eb0fc8e7170e
status: affected
versionType: git
version: 69aba7948cbe
lessThan: 0594f1d048d8
status: affected
versionType: git
version: 69aba7948cbe
lessThan: 57e48886401b
status: affected
versionType: git
version: 69aba7948cbe
lessThan: 0e822e5413da
status: affected
versionType: git
version: 69aba7948cbe
lessThan: 5d388fa01fa6
status: affected
versionType: git
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions: version: 4.3
status: affected
version: 0
lessThan: 4.3
status: unaffected
versionType: custom
version: 4.4.290
lessThanOrEqual: 4.4.*
status: unaffected
versionType: custom
version: 4.9.288
lessThanOrEqual: 4.9.*
status: unaffected
versionType: custom
version: 4.14.252
lessThanOrEqual: 4.14.*
status: unaffected
versionType: custom
version: 4.19.213
lessThanOrEqual: 4.19.*
status: unaffected
versionType: custom
version: 5.4.155
lessThanOrEqual: 5.4.*
status: unaffected
versionType: custom
version: 5.10.75
lessThanOrEqual: 5.10.*
status: unaffected
versionType: custom
version: 5.14.14
lessThanOrEqual: 5.14.*
status: unaffected
versionType: custom
version: 5.15
lessThanOrEqual: *
status: unaffected
versionType: original_commit_for_fix
title: nvmem: Fix shift-out-of-bound (UBSAN) with byte size cells
x_generator: engine: bippy-d175d3acf727