fkie_cve-2025-40008
Vulnerability from fkie_nvd
Published
2025-10-20 16:15
Modified
2025-10-21 19:31
Severity ?
Summary
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5855792c6bb9a825607845db3feaddaff0414ec3
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/85e1ff61060a765d91ee62dc5606d4d547d9d105
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/df1fa034c0fc229a63d01ffb20bb919b839cb576
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e6684ed39edc35401a3341f85b1ab50a6f89a45d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f84e48707051812289b6c2684d4df2daa9d3bfbc
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nkmsan: fix out-of-bounds access to shadow memory\n\nRunning sha224_kunit on a KMSAN-enabled kernel results in a crash in\nkmsan_internal_set_shadow_origin():\n\n    BUG: unable to handle page fault for address: ffffbc3840291000\n    #PF: supervisor read access in kernel mode\n    #PF: error_code(0x0000) - not-present page\n    PGD 1810067 P4D 1810067 PUD 192d067 PMD 3c17067 PTE 0\n    Oops: 0000 [#1] SMP NOPTI\n    CPU: 0 UID: 0 PID: 81 Comm: kunit_try_catch Tainted: G                 N  6.17.0-rc3 #10 PREEMPT(voluntary)\n    Tainted: [N]=TEST\n    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\n    RIP: 0010:kmsan_internal_set_shadow_origin+0x91/0x100\n    [...]\n    Call Trace:\n    \u003cTASK\u003e\n    __msan_memset+0xee/0x1a0\n    sha224_final+0x9e/0x350\n    test_hash_buffer_overruns+0x46f/0x5f0\n    ? kmsan_get_shadow_origin_ptr+0x46/0xa0\n    ? __pfx_test_hash_buffer_overruns+0x10/0x10\n    kunit_try_run_case+0x198/0xa00\n\nThis occurs when memset() is called on a buffer that is not 4-byte aligned\nand extends to the end of a guard page, i.e.  the next page is unmapped.\n\nThe bug is that the loop at the end of kmsan_internal_set_shadow_origin()\naccesses the wrong shadow memory bytes when the address is not 4-byte\naligned.  Since each 4 bytes are associated with an origin, it rounds the\naddress and size so that it can access all the origins that contain the\nbuffer.  However, when it checks the corresponding shadow bytes for a\nparticular origin, it incorrectly uses the original unrounded shadow\naddress.  This results in reads from shadow memory beyond the end of the\nbuffer\u0027s shadow memory, which crashes when that memory is not mapped.\n\nTo fix this, correctly align the shadow address before accessing the 4\nshadow bytes corresponding to each origin."
    }
  ],
  "id": "CVE-2025-40008",
  "lastModified": "2025-10-21T19:31:25.450",
  "metrics": {},
  "published": "2025-10-20T16:15:37.480",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5855792c6bb9a825607845db3feaddaff0414ec3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/85e1ff61060a765d91ee62dc5606d4d547d9d105"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/df1fa034c0fc229a63d01ffb20bb919b839cb576"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e6684ed39edc35401a3341f85b1ab50a6f89a45d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f84e48707051812289b6c2684d4df2daa9d3bfbc"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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