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CVE PROGRAM SOURCE RECORDUnscored

CVE-2025-40008

kmsan: fix out-of-bounds access to shadow memory

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: kmsan: fix out-of-bounds access to shadow memory Running sha224_kunit on a KMSAN-enabled kernel results in a crash in kmsan_internal_set_shadow_origin(): BUG: unable to handle page fault for address: ffffbc3840291000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 1810067 P4D 1810067 PUD 192d067 PMD 3c17067 PTE 0 Oops: 0000 [#1] SMP NOPTI CPU: 0 UID: 0 PID: 81 Comm: kunit_try_catch Tainted: G N 6.17.0-rc3 #10 PREEMPT(voluntary) Tainted: [N]=TEST Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 RIP: 0010:kmsan_internal_set_shadow_origin+0x91/0x100 [...] Call Trace: <TASK> __msan_memset+0xee/0x1a0 sha224_final+0x9e/0x350 test_hash_buffer_overruns+0x46f/0x5f0 ? kmsan_get_shadow_origin_ptr+0x46/0xa0 ? __pfx_test_hash_buffer_overruns+0x10/0x10 kunit_try_run_case+0x198/0xa00 This occurs when memset() is called on a buffer that is not 4-byte aligned and extends to the end of a guard page, i.e. the next page is unmapped. The bug is that the loop at the end of kmsan_internal_set_shadow_origin() accesses the wrong shadow memory bytes when the address is not 4-byte aligned. Since each 4 bytes are associated with an origin, it rounds the address and size so that it can access all the origins that contain the buffer. However, when it checks the corresponding shadow bytes for a particular origin, it incorrectly uses the original unrounded shadow address. This results in reads from shadow memory beyond the end of the buffer's shadow memory, which crashes when that memory is not mapped. To fix this, correctly align the shadow address before accessing the 4 shadow bytes corresponding to each origin.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 9ff078f5bad8990091f1639347de5e02636e9536 to < e6684ed39edc35401a3341f85b1ab50a6f89a45daffected
  • 19e85d939001946671643f4c16e1de8c633a6ce0 to < df1fa034c0fc229a63d01ffb20bb919b839cb576affected
  • 2ef3cec44c60ae171b287db7fc2aa341586d65ba to < f84e48707051812289b6c2684d4df2daa9d3bfbcaffected
  • 2ef3cec44c60ae171b287db7fc2aa341586d65ba to < 5855792c6bb9a825607845db3feaddaff0414ec3affected
  • 2ef3cec44c60ae171b287db7fc2aa341586d65ba to < 85e1ff61060a765d91ee62dc5606d4d547d9d105affected
  • abeede7011da6c88e83ed260b909c140b8c9c250affected
  • 6.1.94 to < 6.1.155affected
  • 6.6.34 to < 6.6.109affected
  • 6.9.5 to < 6.10affected

Linux Linux

Default version status: affected

  • 6.10affected
  • 0 to < 6.10unaffected
  • 6.1.155 to ≤ 6.1.*unaffected
  • 6.6.109 to ≤ 6.6.*unaffected
  • 6.12.50 to ≤ 6.12.*unaffected
  • 6.16.10 to ≤ 6.16.*unaffected
  • 6.17 to ≤ *unaffected

References