CVE-2025-40295 (GCVE-0-2025-40295)
Vulnerability from cvelistv5
Published
2025-12-08 00:46
Modified
2025-12-08 00:46
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: fscrypt: fix left shift underflow when inode->i_blkbits > PAGE_SHIFT When simulating an nvme device on qemu with both logical_block_size and physical_block_size set to 8 KiB, an error trace appears during partition table reading at boot time. The issue is caused by inode->i_blkbits being larger than PAGE_SHIFT, which leads to a left shift of -1 and triggering a UBSAN warning. [ 2.697306] ------------[ cut here ]------------ [ 2.697309] UBSAN: shift-out-of-bounds in fs/crypto/inline_crypt.c:336:37 [ 2.697311] shift exponent -1 is negative [ 2.697315] CPU: 3 UID: 0 PID: 274 Comm: (udev-worker) Not tainted 6.18.0-rc2+ #34 PREEMPT(voluntary) [ 2.697317] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 2.697320] Call Trace: [ 2.697324] <TASK> [ 2.697325] dump_stack_lvl+0x76/0xa0 [ 2.697340] dump_stack+0x10/0x20 [ 2.697342] __ubsan_handle_shift_out_of_bounds+0x1e3/0x390 [ 2.697351] bh_get_inode_and_lblk_num.cold+0x12/0x94 [ 2.697359] fscrypt_set_bio_crypt_ctx_bh+0x44/0x90 [ 2.697365] submit_bh_wbc+0xb6/0x190 [ 2.697370] block_read_full_folio+0x194/0x270 [ 2.697371] ? __pfx_blkdev_get_block+0x10/0x10 [ 2.697375] ? __pfx_blkdev_read_folio+0x10/0x10 [ 2.697377] blkdev_read_folio+0x18/0x30 [ 2.697379] filemap_read_folio+0x40/0xe0 [ 2.697382] filemap_get_pages+0x5ef/0x7a0 [ 2.697385] ? mmap_region+0x63/0xd0 [ 2.697389] filemap_read+0x11d/0x520 [ 2.697392] blkdev_read_iter+0x7c/0x180 [ 2.697393] vfs_read+0x261/0x390 [ 2.697397] ksys_read+0x71/0xf0 [ 2.697398] __x64_sys_read+0x19/0x30 [ 2.697399] x64_sys_call+0x1e88/0x26a0 [ 2.697405] do_syscall_64+0x80/0x670 [ 2.697410] ? __x64_sys_newfstat+0x15/0x20 [ 2.697414] ? x64_sys_call+0x204a/0x26a0 [ 2.697415] ? do_syscall_64+0xb8/0x670 [ 2.697417] ? irqentry_exit_to_user_mode+0x2e/0x2a0 [ 2.697420] ? irqentry_exit+0x43/0x50 [ 2.697421] ? exc_page_fault+0x90/0x1b0 [ 2.697422] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 2.697425] RIP: 0033:0x75054cba4a06 [ 2.697426] Code: 5d e8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 19 83 e2 39 83 fa 08 75 11 e8 26 ff ff ff 66 0f 1f 44 00 00 48 8b 45 10 0f 05 <48> 8b 5d f8 c9 c3 0f 1f 40 00 f3 0f 1e fa 55 48 89 e5 48 83 ec 08 [ 2.697427] RSP: 002b:00007fff973723a0 EFLAGS: 00000202 ORIG_RAX: 0000000000000000 [ 2.697430] RAX: ffffffffffffffda RBX: 00005ea9a2c02760 RCX: 000075054cba4a06 [ 2.697432] RDX: 0000000000002000 RSI: 000075054c190000 RDI: 000000000000001b [ 2.697433] RBP: 00007fff973723c0 R08: 0000000000000000 R09: 0000000000000000 [ 2.697434] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 [ 2.697434] R13: 00005ea9a2c027c0 R14: 00005ea9a2be5608 R15: 00005ea9a2be55f0 [ 2.697436] </TASK> [ 2.697436] ---[ end trace ]--- This situation can happen for block devices because when CONFIG_TRANSPARENT_HUGEPAGE is enabled, the maximum logical_block_size is 64 KiB. set_init_blocksize() then sets the block device inode->i_blkbits to 13, which is within this limit. File I/O does not trigger this problem because for filesystems that do not support the FS_LBS feature, sb_set_blocksize() prevents sb->s_blocksize_bits from being larger than PAGE_SHIFT. During inode allocation, alloc_inode()->inode_init_always() assigns inode->i_blkbits from sb->s_blocksize_bits. Currently, only xfs_fs_type has the FS_LBS flag, and since xfs I/O paths do not reach submit_bh_wbc(), it does not hit the left-shift underflow issue. [EB: use folio_pos() and consolidate the two shifts by i_blkbits]
References
Impacted products
Vendor Product Version
Linux Linux Version: 47dd67532303803a87f43195e088b3b4bcf0454d
Version: 47dd67532303803a87f43195e088b3b4bcf0454d
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/crypto/inline_crypt.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "dde026c5d2a5870f97924d5b512adf2b93fb7153",
              "status": "affected",
              "version": "47dd67532303803a87f43195e088b3b4bcf0454d",
              "versionType": "git"
            },
            {
              "lessThan": "1e39da974ce621ed874c6d3aaf65ad14848c9f0d",
              "status": "affected",
              "version": "47dd67532303803a87f43195e088b3b4bcf0454d",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/crypto/inline_crypt.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.8",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfscrypt: fix left shift underflow when inode-\u003ei_blkbits \u003e PAGE_SHIFT\n\nWhen simulating an nvme device on qemu with both logical_block_size and\nphysical_block_size set to 8 KiB, an error trace appears during\npartition table reading at boot time. The issue is caused by\ninode-\u003ei_blkbits being larger than PAGE_SHIFT, which leads to a left\nshift of -1 and triggering a UBSAN warning.\n\n[    2.697306] ------------[ cut here ]------------\n[    2.697309] UBSAN: shift-out-of-bounds in fs/crypto/inline_crypt.c:336:37\n[    2.697311] shift exponent -1 is negative\n[    2.697315] CPU: 3 UID: 0 PID: 274 Comm: (udev-worker) Not tainted 6.18.0-rc2+ #34 PREEMPT(voluntary)\n[    2.697317] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\n[    2.697320] Call Trace:\n[    2.697324]  \u003cTASK\u003e\n[    2.697325]  dump_stack_lvl+0x76/0xa0\n[    2.697340]  dump_stack+0x10/0x20\n[    2.697342]  __ubsan_handle_shift_out_of_bounds+0x1e3/0x390\n[    2.697351]  bh_get_inode_and_lblk_num.cold+0x12/0x94\n[    2.697359]  fscrypt_set_bio_crypt_ctx_bh+0x44/0x90\n[    2.697365]  submit_bh_wbc+0xb6/0x190\n[    2.697370]  block_read_full_folio+0x194/0x270\n[    2.697371]  ? __pfx_blkdev_get_block+0x10/0x10\n[    2.697375]  ? __pfx_blkdev_read_folio+0x10/0x10\n[    2.697377]  blkdev_read_folio+0x18/0x30\n[    2.697379]  filemap_read_folio+0x40/0xe0\n[    2.697382]  filemap_get_pages+0x5ef/0x7a0\n[    2.697385]  ? mmap_region+0x63/0xd0\n[    2.697389]  filemap_read+0x11d/0x520\n[    2.697392]  blkdev_read_iter+0x7c/0x180\n[    2.697393]  vfs_read+0x261/0x390\n[    2.697397]  ksys_read+0x71/0xf0\n[    2.697398]  __x64_sys_read+0x19/0x30\n[    2.697399]  x64_sys_call+0x1e88/0x26a0\n[    2.697405]  do_syscall_64+0x80/0x670\n[    2.697410]  ? __x64_sys_newfstat+0x15/0x20\n[    2.697414]  ? x64_sys_call+0x204a/0x26a0\n[    2.697415]  ? do_syscall_64+0xb8/0x670\n[    2.697417]  ? irqentry_exit_to_user_mode+0x2e/0x2a0\n[    2.697420]  ? irqentry_exit+0x43/0x50\n[    2.697421]  ? exc_page_fault+0x90/0x1b0\n[    2.697422]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n[    2.697425] RIP: 0033:0x75054cba4a06\n[    2.697426] Code: 5d e8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 19 83 e2 39 83 fa 08 75 11 e8 26 ff ff ff 66 0f 1f 44 00 00 48 8b 45 10 0f 05 \u003c48\u003e 8b 5d f8 c9 c3 0f 1f 40 00 f3 0f 1e fa 55 48 89 e5 48 83 ec 08\n[    2.697427] RSP: 002b:00007fff973723a0 EFLAGS: 00000202 ORIG_RAX: 0000000000000000\n[    2.697430] RAX: ffffffffffffffda RBX: 00005ea9a2c02760 RCX: 000075054cba4a06\n[    2.697432] RDX: 0000000000002000 RSI: 000075054c190000 RDI: 000000000000001b\n[    2.697433] RBP: 00007fff973723c0 R08: 0000000000000000 R09: 0000000000000000\n[    2.697434] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000\n[    2.697434] R13: 00005ea9a2c027c0 R14: 00005ea9a2be5608 R15: 00005ea9a2be55f0\n[    2.697436]  \u003c/TASK\u003e\n[    2.697436] ---[ end trace ]---\n\nThis situation can happen for block devices because when\nCONFIG_TRANSPARENT_HUGEPAGE is enabled, the maximum logical_block_size\nis 64 KiB. set_init_blocksize() then sets the block device\ninode-\u003ei_blkbits to 13, which is within this limit.\n\nFile I/O does not trigger this problem because for filesystems that do\nnot support the FS_LBS feature, sb_set_blocksize() prevents\nsb-\u003es_blocksize_bits from being larger than PAGE_SHIFT. During inode\nallocation, alloc_inode()-\u003einode_init_always() assigns inode-\u003ei_blkbits\nfrom sb-\u003es_blocksize_bits. Currently, only xfs_fs_type has the FS_LBS\nflag, and since xfs I/O paths do not reach submit_bh_wbc(), it does not\nhit the left-shift underflow issue.\n\n[EB: use folio_pos() and consolidate the two shifts by i_blkbits]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-12-08T00:46:18.950Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/dde026c5d2a5870f97924d5b512adf2b93fb7153"
        },
        {
          "url": "https://git.kernel.org/stable/c/1e39da974ce621ed874c6d3aaf65ad14848c9f0d"
        }
      ],
      "title": "fscrypt: fix left shift underflow when inode-\u003ei_blkbits \u003e PAGE_SHIFT",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40295",
    "datePublished": "2025-12-08T00:46:18.950Z",
    "dateReserved": "2025-04-16T07:20:57.185Z",
    "dateUpdated": "2025-12-08T00:46:18.950Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40295\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-08T01:16:01.557\",\"lastModified\":\"2025-12-08T18:26:49.133\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nfscrypt: fix left shift underflow when inode-\u003ei_blkbits \u003e PAGE_SHIFT\\n\\nWhen simulating an nvme device on qemu with both logical_block_size and\\nphysical_block_size set to 8 KiB, an error trace appears during\\npartition table reading at boot time. The issue is caused by\\ninode-\u003ei_blkbits being larger than PAGE_SHIFT, which leads to a left\\nshift of -1 and triggering a UBSAN warning.\\n\\n[    2.697306] ------------[ cut here ]------------\\n[    2.697309] UBSAN: shift-out-of-bounds in fs/crypto/inline_crypt.c:336:37\\n[    2.697311] shift exponent -1 is negative\\n[    2.697315] CPU: 3 UID: 0 PID: 274 Comm: (udev-worker) Not tainted 6.18.0-rc2+ #34 PREEMPT(voluntary)\\n[    2.697317] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\\n[    2.697320] Call Trace:\\n[    2.697324]  \u003cTASK\u003e\\n[    2.697325]  dump_stack_lvl+0x76/0xa0\\n[    2.697340]  dump_stack+0x10/0x20\\n[    2.697342]  __ubsan_handle_shift_out_of_bounds+0x1e3/0x390\\n[    2.697351]  bh_get_inode_and_lblk_num.cold+0x12/0x94\\n[    2.697359]  fscrypt_set_bio_crypt_ctx_bh+0x44/0x90\\n[    2.697365]  submit_bh_wbc+0xb6/0x190\\n[    2.697370]  block_read_full_folio+0x194/0x270\\n[    2.697371]  ? __pfx_blkdev_get_block+0x10/0x10\\n[    2.697375]  ? __pfx_blkdev_read_folio+0x10/0x10\\n[    2.697377]  blkdev_read_folio+0x18/0x30\\n[    2.697379]  filemap_read_folio+0x40/0xe0\\n[    2.697382]  filemap_get_pages+0x5ef/0x7a0\\n[    2.697385]  ? mmap_region+0x63/0xd0\\n[    2.697389]  filemap_read+0x11d/0x520\\n[    2.697392]  blkdev_read_iter+0x7c/0x180\\n[    2.697393]  vfs_read+0x261/0x390\\n[    2.697397]  ksys_read+0x71/0xf0\\n[    2.697398]  __x64_sys_read+0x19/0x30\\n[    2.697399]  x64_sys_call+0x1e88/0x26a0\\n[    2.697405]  do_syscall_64+0x80/0x670\\n[    2.697410]  ? __x64_sys_newfstat+0x15/0x20\\n[    2.697414]  ? x64_sys_call+0x204a/0x26a0\\n[    2.697415]  ? do_syscall_64+0xb8/0x670\\n[    2.697417]  ? irqentry_exit_to_user_mode+0x2e/0x2a0\\n[    2.697420]  ? irqentry_exit+0x43/0x50\\n[    2.697421]  ? exc_page_fault+0x90/0x1b0\\n[    2.697422]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\\n[    2.697425] RIP: 0033:0x75054cba4a06\\n[    2.697426] Code: 5d e8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 19 83 e2 39 83 fa 08 75 11 e8 26 ff ff ff 66 0f 1f 44 00 00 48 8b 45 10 0f 05 \u003c48\u003e 8b 5d f8 c9 c3 0f 1f 40 00 f3 0f 1e fa 55 48 89 e5 48 83 ec 08\\n[    2.697427] RSP: 002b:00007fff973723a0 EFLAGS: 00000202 ORIG_RAX: 0000000000000000\\n[    2.697430] RAX: ffffffffffffffda RBX: 00005ea9a2c02760 RCX: 000075054cba4a06\\n[    2.697432] RDX: 0000000000002000 RSI: 000075054c190000 RDI: 000000000000001b\\n[    2.697433] RBP: 00007fff973723c0 R08: 0000000000000000 R09: 0000000000000000\\n[    2.697434] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000\\n[    2.697434] R13: 00005ea9a2c027c0 R14: 00005ea9a2be5608 R15: 00005ea9a2be55f0\\n[    2.697436]  \u003c/TASK\u003e\\n[    2.697436] ---[ end trace ]---\\n\\nThis situation can happen for block devices because when\\nCONFIG_TRANSPARENT_HUGEPAGE is enabled, the maximum logical_block_size\\nis 64 KiB. set_init_blocksize() then sets the block device\\ninode-\u003ei_blkbits to 13, which is within this limit.\\n\\nFile I/O does not trigger this problem because for filesystems that do\\nnot support the FS_LBS feature, sb_set_blocksize() prevents\\nsb-\u003es_blocksize_bits from being larger than PAGE_SHIFT. During inode\\nallocation, alloc_inode()-\u003einode_init_always() assigns inode-\u003ei_blkbits\\nfrom sb-\u003es_blocksize_bits. Currently, only xfs_fs_type has the FS_LBS\\nflag, and since xfs I/O paths do not reach submit_bh_wbc(), it does not\\nhit the left-shift underflow issue.\\n\\n[EB: use folio_pos() and consolidate the two shifts by i_blkbits]\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1e39da974ce621ed874c6d3aaf65ad14848c9f0d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dde026c5d2a5870f97924d5b512adf2b93fb7153\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.