CVE-2025-21809 (GCVE-0-2025-21809)
Vulnerability from cvelistv5
Published
2025-02-27 20:01
Modified
2026-05-23 15:57
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: rxrpc, afs: Fix peer hash locking vs RCU callback In its address list, afs now retains pointers to and refs on one or more rxrpc_peer objects. The address list is freed under RCU and at this time, it puts the refs on those peers. Now, when an rxrpc_peer object runs out of refs, it gets removed from the peer hash table and, for that, rxrpc has to take a spinlock. However, it is now being called from afs's RCU cleanup, which takes place in BH context - but it is just taking an ordinary spinlock. The put may also be called from non-BH context, and so there exists the possibility of deadlock if the BH-based RCU cleanup happens whilst the hash spinlock is held. This led to the attached lockdep complaint. Fix this by changing spinlocks of rxnet->peer_hash_lock back to BH-disabling locks. ================================ WARNING: inconsistent lock state 6.13.0-rc5-build2+ #1223 Tainted: G E -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff88810babe228 (&rxnet->peer_hash_lock){+.?.}-{3:3}, at: rxrpc_put_peer+0xcb/0x180 {SOFTIRQ-ON-W} state was registered at: mark_usage+0x164/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_peer_keepalive_worker+0x144/0x440 process_one_work+0x486/0x7c0 process_scheduled_works+0x73/0x90 worker_thread+0x1c8/0x2a0 kthread+0x19b/0x1b0 ret_from_fork+0x24/0x40 ret_from_fork_asm+0x1a/0x30 irq event stamp: 972402 hardirqs last enabled at (972402): [<ffffffff8244360e>] _raw_spin_unlock_irqrestore+0x2e/0x50 hardirqs last disabled at (972401): [<ffffffff82443328>] _raw_spin_lock_irqsave+0x18/0x60 softirqs last enabled at (972300): [<ffffffff810ffbbe>] handle_softirqs+0x3ee/0x430 softirqs last disabled at (972313): [<ffffffff810ffc54>] __irq_exit_rcu+0x44/0x110 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&rxnet->peer_hash_lock); <Interrupt> lock(&rxnet->peer_hash_lock); *** DEADLOCK *** 1 lock held by swapper/1/0: #0: ffffffff83576be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x7/0x30 stack backtrace: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G E 6.13.0-rc5-build2+ #1223 Tainted: [E]=UNSIGNED_MODULE Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014 Call Trace: <IRQ> dump_stack_lvl+0x57/0x80 print_usage_bug.part.0+0x227/0x240 valid_state+0x53/0x70 mark_lock_irq+0xa5/0x2f0 mark_lock+0xf7/0x170 mark_usage+0xe1/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_put_peer+0xcb/0x180 afs_free_addrlist+0x46/0x90 [kafs] rcu_do_batch+0x2d2/0x640 rcu_core+0x2f7/0x350 handle_softirqs+0x1ee/0x430 __irq_exit_rcu+0x44/0x110 irq_exit_rcu+0xa/0x30 sysvec_apic_timer_interrupt+0x7f/0xa0 </IRQ>
References
Impacted products
Vendor Product Version
Linux Linux Version: 72904d7b9bfbf2dd146254edea93958bc35bbbfe
Version: 72904d7b9bfbf2dd146254edea93958bc35bbbfe
Version: 72904d7b9bfbf2dd146254edea93958bc35bbbfe
Version: 056fc740be000d39a7dba700a935f3bbfbc664e6
Version: 6.7.3   ≤
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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "LOCAL",
              "availabilityImpact": "HIGH",
              "baseScore": 5.5,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "LOW",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2025-21809",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-10-01T19:28:41.037357Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-667",
                "description": "CWE-667 Improper Locking",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-10-01T19:36:38.646Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/rxrpc/peer_event.c",
            "net/rxrpc/peer_object.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "10ba5a3d57af20e494e0d979d1894260989235dd",
              "status": "affected",
              "version": "72904d7b9bfbf2dd146254edea93958bc35bbbfe",
              "versionType": "git"
            },
            {
              "lessThan": "0e77dd41689637ac4e1b8fe0f27541f373640855",
              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "79d458c13056559d49b5e41fbc4b6890e68cf65b",
              "status": "affected",
              "version": "72904d7b9bfbf2dd146254edea93958bc35bbbfe",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "056fc740be000d39a7dba700a935f3bbfbc664e6",
              "versionType": "git"
            },
            {
              "lessThan": "6.8",
              "status": "affected",
              "version": "6.7.3",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/rxrpc/peer_event.c",
            "net/rxrpc/peer_object.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "lessThan": "6.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.13.*",
              "status": "unaffected",
              "version": "6.13.2",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.14",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.13",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.13.2",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.7.3",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc, afs: Fix peer hash locking vs RCU callback\n\nIn its address list, afs now retains pointers to and refs on one or more\nrxrpc_peer objects.  The address list is freed under RCU and at this time,\nit puts the refs on those peers.\n\nNow, when an rxrpc_peer object runs out of refs, it gets removed from the\npeer hash table and, for that, rxrpc has to take a spinlock.  However, it\nis now being called from afs\u0027s RCU cleanup, which takes place in BH\ncontext - but it is just taking an ordinary spinlock.\n\nThe put may also be called from non-BH context, and so there exists the\npossibility of deadlock if the BH-based RCU cleanup happens whilst the hash\nspinlock is held.  This led to the attached lockdep complaint.\n\nFix this by changing spinlocks of rxnet-\u003epeer_hash_lock back to\nBH-disabling locks.\n\n    ================================\n    WARNING: inconsistent lock state\n    6.13.0-rc5-build2+ #1223 Tainted: G            E\n    --------------------------------\n    inconsistent {SOFTIRQ-ON-W} -\u003e {IN-SOFTIRQ-W} usage.\n    swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes:\n    ffff88810babe228 (\u0026rxnet-\u003epeer_hash_lock){+.?.}-{3:3}, at: rxrpc_put_peer+0xcb/0x180\n    {SOFTIRQ-ON-W} state was registered at:\n      mark_usage+0x164/0x180\n      __lock_acquire+0x544/0x990\n      lock_acquire.part.0+0x103/0x280\n      _raw_spin_lock+0x2f/0x40\n      rxrpc_peer_keepalive_worker+0x144/0x440\n      process_one_work+0x486/0x7c0\n      process_scheduled_works+0x73/0x90\n      worker_thread+0x1c8/0x2a0\n      kthread+0x19b/0x1b0\n      ret_from_fork+0x24/0x40\n      ret_from_fork_asm+0x1a/0x30\n    irq event stamp: 972402\n    hardirqs last  enabled at (972402): [\u003cffffffff8244360e\u003e] _raw_spin_unlock_irqrestore+0x2e/0x50\n    hardirqs last disabled at (972401): [\u003cffffffff82443328\u003e] _raw_spin_lock_irqsave+0x18/0x60\n    softirqs last  enabled at (972300): [\u003cffffffff810ffbbe\u003e] handle_softirqs+0x3ee/0x430\n    softirqs last disabled at (972313): [\u003cffffffff810ffc54\u003e] __irq_exit_rcu+0x44/0x110\n\n    other info that might help us debug this:\n     Possible unsafe locking scenario:\n           CPU0\n           ----\n      lock(\u0026rxnet-\u003epeer_hash_lock);\n      \u003cInterrupt\u003e\n        lock(\u0026rxnet-\u003epeer_hash_lock);\n\n     *** DEADLOCK ***\n    1 lock held by swapper/1/0:\n     #0: ffffffff83576be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x7/0x30\n\n    stack backtrace:\n    CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G            E      6.13.0-rc5-build2+ #1223\n    Tainted: [E]=UNSIGNED_MODULE\n    Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014\n    Call Trace:\n     \u003cIRQ\u003e\n     dump_stack_lvl+0x57/0x80\n     print_usage_bug.part.0+0x227/0x240\n     valid_state+0x53/0x70\n     mark_lock_irq+0xa5/0x2f0\n     mark_lock+0xf7/0x170\n     mark_usage+0xe1/0x180\n     __lock_acquire+0x544/0x990\n     lock_acquire.part.0+0x103/0x280\n     _raw_spin_lock+0x2f/0x40\n     rxrpc_put_peer+0xcb/0x180\n     afs_free_addrlist+0x46/0x90 [kafs]\n     rcu_do_batch+0x2d2/0x640\n     rcu_core+0x2f7/0x350\n     handle_softirqs+0x1ee/0x430\n     __irq_exit_rcu+0x44/0x110\n     irq_exit_rcu+0xa/0x30\n     sysvec_apic_timer_interrupt+0x7f/0xa0\n     \u003c/IRQ\u003e"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-23T15:57:12.005Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/10ba5a3d57af20e494e0d979d1894260989235dd"
        },
        {
          "url": "https://git.kernel.org/stable/c/0e77dd41689637ac4e1b8fe0f27541f373640855"
        },
        {
          "url": "https://git.kernel.org/stable/c/79d458c13056559d49b5e41fbc4b6890e68cf65b"
        }
      ],
      "title": "rxrpc, afs: Fix peer hash locking vs RCU callback",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-21809",
    "datePublished": "2025-02-27T20:01:00.969Z",
    "dateReserved": "2024-12-29T08:45:45.772Z",
    "dateUpdated": "2026-05-23T15:57:12.005Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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