CVE-2025-38525 (GCVE-0-2025-38525)
Vulnerability from cvelistv5
Published
2025-08-16 11:12
Modified
2026-08-10 12:10
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix irq-disabled in local_bh_enable() The rxrpc_assess_MTU_size() function calls down into the IP layer to find out the MTU size for a route. When accepting an incoming call, this is called from rxrpc_new_incoming_call() which holds interrupts disabled across the code that calls down to it. Unfortunately, the IP layer uses local_bh_enable() which, config dependent, throws a warning if IRQs are enabled: WARNING: CPU: 1 PID: 5544 at kernel/softirq.c:387 __local_bh_enable_ip+0x43/0xd0 ... RIP: 0010:__local_bh_enable_ip+0x43/0xd0 ... Call Trace: <TASK> rt_cache_route+0x7e/0xa0 rt_set_nexthop.isra.0+0x3b3/0x3f0 __mkroute_output+0x43a/0x460 ip_route_output_key_hash+0xf7/0x140 ip_route_output_flow+0x1b/0x90 rxrpc_assess_MTU_size.isra.0+0x2a0/0x590 rxrpc_new_incoming_peer+0x46/0x120 rxrpc_alloc_incoming_call+0x1b1/0x400 rxrpc_new_incoming_call+0x1da/0x5e0 rxrpc_input_packet+0x827/0x900 rxrpc_io_thread+0x403/0xb60 kthread+0x2f7/0x310 ret_from_fork+0x2a/0x230 ret_from_fork_asm+0x1a/0x30 ... hardirqs last enabled at (23): _raw_spin_unlock_irq+0x24/0x50 hardirqs last disabled at (24): _raw_read_lock_irq+0x17/0x70 softirqs last enabled at (0): copy_process+0xc61/0x2730 softirqs last disabled at (25): rt_add_uncached_list+0x3c/0x90 Fix this by moving the call to rxrpc_assess_MTU_size() out of rxrpc_init_peer() and further up the stack where it can be done without interrupts disabled. It shouldn't be a problem for rxrpc_new_incoming_call() to do it after the locks are dropped as pmtud is going to be performed by the I/O thread - and we're in the I/O thread at this point.
References
Impacted products
Vendor Product Version
Linux Linux Version: 77433b730970ca6e51d03016e830d8ab1b22685a
Version: 09c59a82298f424f6212c67fbea531853e88ce6c
Version: a2ea9a9072607c2fd6442bd1ffb4dbdbf882aed7
Version: a2ea9a9072607c2fd6442bd1ffb4dbdbf882aed7
Version: 6.6.148   ≤
Version: 6.12.101   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/rxrpc/ar-internal.h",
            "net/rxrpc/call_accept.c",
            "net/rxrpc/peer_object.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            {
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              "status": "affected",
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              "status": "affected",
              "version": "6.12.101",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/rxrpc/ar-internal.h",
            "net/rxrpc/call_accept.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": "6.14"
            },
            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.151",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.103",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.15.*",
              "status": "unaffected",
              "version": "6.15.8",
              "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": "6.6.151",
                  "versionStartIncluding": "6.6.148",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.103",
                  "versionStartIncluding": "6.12.101",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.15.8",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Fix irq-disabled in local_bh_enable()\n\nThe rxrpc_assess_MTU_size() function calls down into the IP layer to find\nout the MTU size for a route.  When accepting an incoming call, this is\ncalled from rxrpc_new_incoming_call() which holds interrupts disabled\nacross the code that calls down to it.  Unfortunately, the IP layer uses\nlocal_bh_enable() which, config dependent, throws a warning if IRQs are\nenabled:\n\nWARNING: CPU: 1 PID: 5544 at kernel/softirq.c:387 __local_bh_enable_ip+0x43/0xd0\n...\nRIP: 0010:__local_bh_enable_ip+0x43/0xd0\n...\nCall Trace:\n \u003cTASK\u003e\n rt_cache_route+0x7e/0xa0\n rt_set_nexthop.isra.0+0x3b3/0x3f0\n __mkroute_output+0x43a/0x460\n ip_route_output_key_hash+0xf7/0x140\n ip_route_output_flow+0x1b/0x90\n rxrpc_assess_MTU_size.isra.0+0x2a0/0x590\n rxrpc_new_incoming_peer+0x46/0x120\n rxrpc_alloc_incoming_call+0x1b1/0x400\n rxrpc_new_incoming_call+0x1da/0x5e0\n rxrpc_input_packet+0x827/0x900\n rxrpc_io_thread+0x403/0xb60\n kthread+0x2f7/0x310\n ret_from_fork+0x2a/0x230\n ret_from_fork_asm+0x1a/0x30\n...\nhardirqs last  enabled at (23): _raw_spin_unlock_irq+0x24/0x50\nhardirqs last disabled at (24): _raw_read_lock_irq+0x17/0x70\nsoftirqs last  enabled at (0): copy_process+0xc61/0x2730\nsoftirqs last disabled at (25): rt_add_uncached_list+0x3c/0x90\n\nFix this by moving the call to rxrpc_assess_MTU_size() out of\nrxrpc_init_peer() and further up the stack where it can be done without\ninterrupts disabled.\n\nIt shouldn\u0027t be a problem for rxrpc_new_incoming_call() to do it after the\nlocks are dropped as pmtud is going to be performed by the I/O thread - and\nwe\u0027re in the I/O thread at this point."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable path is entered directly from `rxrpc_encap_rcv()`/`rxrpc_input_packet()` when an rxrpc DATA packet arrives over UDP from an unknown peer, and kAFS binds its callback-manager service socket to `in6addr_any:7001`, so any routable remote host can reach it.\nAC:L - The attacker fully controls every precondition \u2014 a single crafted rxrpc DATA packet (`callNumber != 0`, `seq == 1`, matching serviceId) from a source port not yet in the peer hash deterministically forces new-peer creation and the MTU assessment under `read_lock_irq()`; no memory layout, timing, or victim state is involved.\nPR:N - `rxrpc_new_incoming_call()` runs entirely before any rxrpc authentication \u2014 the CHALLENGE/RESPONSE handshake is only queued after the call is made live, and `rxrpc_get_incoming_security()` merely validates that the security index is supported, so an unauthenticated off-path attacker suffices.\nUI:N - The AFS/rxrpc service socket is already bound and listening as soon as AFS is in use; processing of the attacker\u0027s packet happens autonomously in the rxrpc I/O kernel thread with no victim action.\nS:U - The fault and its effects are confined to the kernel\u0027s own security authority on the affected host; no VM, IOMMU, or sandbox boundary is crossed.\nC:N - The defect is purely a locking/IRQ-context violation with no out-of-bounds read, use-after-free, or uninitialised data exposure; nothing is leaked to the remote attacker, who cannot observe the kernel log.\nI:N - No memory is corrupted and no attacker-controlled data is written out of bounds \u2014 the peer backlog ring update completes before the offending call, so there is no write primitive or state modification available.\nA:H - `lockdep_assert_irqs_enabled()` WARNs on `CONFIG_PROVE_LOCKING` kernels, which is a hard panic under the widely deployed `panic_on_warn=1`; independently of that config, `do_softirq()`/`handle_softirqs()` re-enables hardirqs and burns up to 2 ms \u00d7 10 restarts of softirq work inside the `read_lock_irq()` + `spin_lock()` section, stalling the rxrpc I/O thread \u2014 and the whole sequence is remotely repeatable at packet rate by rotating source ports."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-10T12:10:47.387Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d94b82d452ca27a200cd67660dc48476386651d8"
        },
        {
          "url": "https://git.kernel.org/stable/c/8ac0b3baa7d8f732bd9e5cbf1d8b57e4802c6b36"
        },
        {
          "url": "https://git.kernel.org/stable/c/2029f21f10dedb88c0f86abffcf8d6c21dcf6040"
        },
        {
          "url": "https://git.kernel.org/stable/c/e4d2878369d590bf8455e3678a644e503172eafa"
        }
      ],
      "title": "rxrpc: Fix irq-disabled in local_bh_enable()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38525",
    "datePublished": "2025-08-16T11:12:19.191Z",
    "dateReserved": "2025-04-16T04:51:24.023Z",
    "dateUpdated": "2026-08-10T12:10:47.387Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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