CVE-2025-38517 (GCVE-0-2025-38517)

Vulnerability from cvelistv5 – Published: 2025-08-16 10:55 – Updated: 2025-08-16 10:55
VLAI?
Title
lib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users()
Summary
In the Linux kernel, the following vulnerability has been resolved: lib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users() alloc_tag_top_users() attempts to lock alloc_tag_cttype->mod_lock even when the alloc_tag_cttype is not allocated because: 1) alloc tagging is disabled because mem profiling is disabled (!alloc_tag_cttype) 2) alloc tagging is enabled, but not yet initialized (!alloc_tag_cttype) 3) alloc tagging is enabled, but failed initialization (!alloc_tag_cttype or IS_ERR(alloc_tag_cttype)) In all cases, alloc_tag_cttype is not allocated, and therefore alloc_tag_top_users() should not attempt to acquire the semaphore. This leads to a crash on memory allocation failure by attempting to acquire a non-existent semaphore: Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#3] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df] CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G D 6.16.0-rc2 #1 VOLUNTARY Tainted: [D]=DIE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:down_read_trylock+0xaa/0x3b0 Code: d0 7c 08 84 d2 0f 85 a0 02 00 00 8b 0d df 31 dd 04 85 c9 75 29 48 b8 00 00 00 00 00 fc ff df 48 8d 6b 68 48 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 88 02 00 00 48 3b 5b 68 0f 85 53 01 00 00 65 ff RSP: 0000:ffff8881002ce9b8 EFLAGS: 00010016 RAX: dffffc0000000000 RBX: 0000000000000070 RCX: 0000000000000000 RDX: 000000000000001b RSI: 000000000000000a RDI: 0000000000000070 RBP: 00000000000000d8 R08: 0000000000000001 R09: ffffed107dde49d1 R10: ffff8883eef24e8b R11: ffff8881002cec20 R12: 1ffff11020059d37 R13: 00000000003fff7b R14: ffff8881002cec20 R15: dffffc0000000000 FS: 00007f963f21d940(0000) GS:ffff888458ca6000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f963f5edf71 CR3: 000000010672c000 CR4: 0000000000350ef0 Call Trace: <TASK> codetag_trylock_module_list+0xd/0x20 alloc_tag_top_users+0x369/0x4b0 __show_mem+0x1cd/0x6e0 warn_alloc+0x2b1/0x390 __alloc_frozen_pages_noprof+0x12b9/0x21a0 alloc_pages_mpol+0x135/0x3e0 alloc_slab_page+0x82/0xe0 new_slab+0x212/0x240 ___slab_alloc+0x82a/0xe00 </TASK> As David Wang points out, this issue became easier to trigger after commit 780138b12381 ("alloc_tag: check mem_profiling_support in alloc_tag_init"). Before the commit, the issue occurred only when it failed to allocate and initialize alloc_tag_cttype or if a memory allocation fails before alloc_tag_init() is called. After the commit, it can be easily triggered when memory profiling is compiled but disabled at boot. To properly determine whether alloc_tag_init() has been called and its data structures initialized, verify that alloc_tag_cttype is a valid pointer before acquiring the semaphore. If the variable is NULL or an error value, it has not been properly initialized. In such a case, just skip and do not attempt to acquire the semaphore. [harry.yoo@oracle.com: v3]
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1438d349d16b78d88f9e978a4a5496f078c8191b , < febc0b5dbabda414565bdfaaaa59d26f787d5fe7 (git)
Affected: 1438d349d16b78d88f9e978a4a5496f078c8191b , < 22bf79c0c2301b6e15a688220284b147774d277e (git)
Affected: 1438d349d16b78d88f9e978a4a5496f078c8191b , < 99af22cd34688cc0d535a1919e0bea4cbc6c1ea1 (git)
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    Linux Linux Affected: 6.10
Unaffected: 0 , < 6.10 (semver)
Unaffected: 6.12.39 , ≤ 6.12.* (semver)
Unaffected: 6.15.7 , ≤ 6.15.* (semver)
Unaffected: 6.16 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "lib/alloc_tag.c"
          ],
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          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "1438d349d16b78d88f9e978a4a5496f078c8191b",
              "versionType": "git"
            },
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              "lessThan": "22bf79c0c2301b6e15a688220284b147774d277e",
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              "version": "1438d349d16b78d88f9e978a4a5496f078c8191b",
              "versionType": "git"
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              "versionType": "git"
            }
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          "product": "Linux",
          "programFiles": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.10"
            },
            {
              "lessThan": "6.10",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.15.*",
              "status": "unaffected",
              "version": "6.15.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.16",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.39",
                  "versionStartIncluding": "6.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.15.7",
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16",
                  "versionStartIncluding": "6.10",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users()\n\nalloc_tag_top_users() attempts to lock alloc_tag_cttype-\u003emod_lock even\nwhen the alloc_tag_cttype is not allocated because:\n\n  1) alloc tagging is disabled because mem profiling is disabled\n     (!alloc_tag_cttype)\n  2) alloc tagging is enabled, but not yet initialized (!alloc_tag_cttype)\n  3) alloc tagging is enabled, but failed initialization\n     (!alloc_tag_cttype or IS_ERR(alloc_tag_cttype))\n\nIn all cases, alloc_tag_cttype is not allocated, and therefore\nalloc_tag_top_users() should not attempt to acquire the semaphore.\n\nThis leads to a crash on memory allocation failure by attempting to\nacquire a non-existent semaphore:\n\n  Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#3] SMP KASAN NOPTI\n  KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df]\n  CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G      D             6.16.0-rc2 #1 VOLUNTARY\n  Tainted: [D]=DIE\n  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014\n  RIP: 0010:down_read_trylock+0xaa/0x3b0\n  Code: d0 7c 08 84 d2 0f 85 a0 02 00 00 8b 0d df 31 dd 04 85 c9 75 29 48 b8 00 00 00 00 00 fc ff df 48 8d 6b 68 48 89 ea 48 c1 ea 03 \u003c80\u003e 3c 02 00 0f 85 88 02 00 00 48 3b 5b 68 0f 85 53 01 00 00 65 ff\n  RSP: 0000:ffff8881002ce9b8 EFLAGS: 00010016\n  RAX: dffffc0000000000 RBX: 0000000000000070 RCX: 0000000000000000\n  RDX: 000000000000001b RSI: 000000000000000a RDI: 0000000000000070\n  RBP: 00000000000000d8 R08: 0000000000000001 R09: ffffed107dde49d1\n  R10: ffff8883eef24e8b R11: ffff8881002cec20 R12: 1ffff11020059d37\n  R13: 00000000003fff7b R14: ffff8881002cec20 R15: dffffc0000000000\n  FS:  00007f963f21d940(0000) GS:ffff888458ca6000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00007f963f5edf71 CR3: 000000010672c000 CR4: 0000000000350ef0\n  Call Trace:\n   \u003cTASK\u003e\n   codetag_trylock_module_list+0xd/0x20\n   alloc_tag_top_users+0x369/0x4b0\n   __show_mem+0x1cd/0x6e0\n   warn_alloc+0x2b1/0x390\n   __alloc_frozen_pages_noprof+0x12b9/0x21a0\n   alloc_pages_mpol+0x135/0x3e0\n   alloc_slab_page+0x82/0xe0\n   new_slab+0x212/0x240\n   ___slab_alloc+0x82a/0xe00\n   \u003c/TASK\u003e\n\nAs David Wang points out, this issue became easier to trigger after commit\n780138b12381 (\"alloc_tag: check mem_profiling_support in alloc_tag_init\").\n\nBefore the commit, the issue occurred only when it failed to allocate and\ninitialize alloc_tag_cttype or if a memory allocation fails before\nalloc_tag_init() is called.  After the commit, it can be easily triggered\nwhen memory profiling is compiled but disabled at boot.\n\nTo properly determine whether alloc_tag_init() has been called and its\ndata structures initialized, verify that alloc_tag_cttype is a valid\npointer before acquiring the semaphore.  If the variable is NULL or an\nerror value, it has not been properly initialized.  In such a case, just\nskip and do not attempt to acquire the semaphore.\n\n[harry.yoo@oracle.com: v3]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-08-16T10:55:04.217Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/febc0b5dbabda414565bdfaaaa59d26f787d5fe7"
        },
        {
          "url": "https://git.kernel.org/stable/c/22bf79c0c2301b6e15a688220284b147774d277e"
        },
        {
          "url": "https://git.kernel.org/stable/c/99af22cd34688cc0d535a1919e0bea4cbc6c1ea1"
        }
      ],
      "title": "lib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38517",
    "datePublished": "2025-08-16T10:55:04.217Z",
    "dateReserved": "2025-04-16T04:51:24.023Z",
    "dateUpdated": "2025-08-16T10:55:04.217Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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