CVE-2026-72121 (GCVE-0-2026-72121)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:52 – Updated: 2026-08-19 16:36
VLAI
Title
can: bcm: add locking when updating filter and timer values
Summary
In the Linux kernel, the following vulnerability has been resolved: can: bcm: add locking when updating filter and timer values KCSAN detected a simultaneous access to timer values that can be overwritten in bcm_rx_setup() when updating timer and filter content while bcm_rx_handler(), bcm_rx_timeout_handler() or bcm_rx_thr_handler() run concurrently on incoming CAN traffic. Protect the timer (ival1/ival2/kt_ival1/kt_ival2/kt_lastmsg) and filter (nframes/flags/frames/last_frames) updates in bcm_rx_setup() with a new per-op bcm_rx_update_lock, taken with the matching scope in the RX handlers. memcpy_from_msg() is staged into a temporary buffer before the lock is taken, since it can sleep and must not run under a spinlock. hrtimer_cancel() is always called without bcm_rx_update_lock held, since bcm_rx_timeout_handler()/bcm_rx_thr_handler() take the same lock and a running callback would otherwise deadlock against the canceller. Also close a related race: bcm_rx_setup() cleared the RTR flag in the stored reply frame's can_id as a separate, unprotected step after the frame content was already installed, so a concurrent bcm_rx_handler() could transmit a stale reply with CAN_RTR_FLAG still set. Fold that normalization into the initial frame preparation instead (on the staged buffer for updates, directly on op->frames pre-registration for new ops), so the installed frame is always atomically self-consistent. bcm_rx_handler()'s RX_RTR_FRAME check now takes a lock-protected snapshot of op->flags before deciding whether to call bcm_can_tx(), but does not hold the lock across that call. Also take a lock-protected snapshot of the currframe in bcm_can_tx() to avoid partly overwrites by content updates in bcm_tx_setup(). Finally check if a TX_RESET_MULTI_IDX/SETTIMER might have reset op->currframe between the two locked sections in bcm_can_tx(). Omit calling hrtimer_forward() with zero interval in bcm_rx_thr_handler(). kt_ival2 may have been concurrently cleared by bcm_rx_setup() before it cancels this timer, so check kt_ival2 inside the bcm_rx_update_lock.
Severity
8.8 (High)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7595de7bc56e0e52b74e56c90f7e247bf626d628 , < 96994180bd7b248b0cc698afe926e23fc1bda59b (git)
Affected: fbd8fdc2b218e979cfe422b139b8f74c12419d1f , < caa8704a7f3cb7806331596195385437126ecb3a (git)
Affected: 2a437b86ac5a9893c902f30ef66815bf13587bf6 , < a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658 (git)
Affected: 76c84c3728178b2d38d5604e399dfe8b0752645e , < a7eb6db1cd3f7b556a301dc1265945ad112089f7 (git)
Affected: cc55dd28c20a6611e30596019b3b2f636819a4c0 , < 834cbca3b12e46887f7a9b35f1981a888360ea4c (git)
Affected: c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7 , < 19b1994069dd29478ba767de1f98f14a088198dc (git)
Affected: c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7 , < fc9f5ee1b073bd233d9c604e338af4ebb42cbc33 (git)
Affected: c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7 , < 749179c2e25b95d22499ed29096b3e02d6dfd2b4 (git)
Affected: 8f1c022541bf5a923c8d6fa483112c15250f30a4 (git)
Affected: c4e8a172501e677ebd8ea9d9161d97dc4df56fbd (git)
Affected: 5.10.238 , < 5.10.265 (semver)
Affected: 5.15.185 , < 5.15.216 (semver)
Affected: 6.1.141 , < 6.1.183 (semver)
Affected: 6.6.93 , < 6.6.148 (semver)
Affected: 6.12.31 , < 6.12.101 (semver)
Affected: 5.4.294 , < 5.5 (semver)
Affected: 6.14.9 , < 6.15 (semver)
guessed Create a notification for this product.
Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 5.10.265 , ≤ 5.10.* (semver)
Unaffected: 5.15.216 , ≤ 5.15.* (semver)
Unaffected: 6.1.183 , ≤ 6.1.* (semver)
Unaffected: 6.6.148 , ≤ 6.6.* (semver)
Unaffected: 6.12.101 , ≤ 6.12.* (semver)
Unaffected: 6.18.42 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/can/bcm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "96994180bd7b248b0cc698afe926e23fc1bda59b",
              "status": "affected",
              "version": "7595de7bc56e0e52b74e56c90f7e247bf626d628",
              "versionType": "git"
            },
            {
              "lessThan": "caa8704a7f3cb7806331596195385437126ecb3a",
              "status": "affected",
              "version": "fbd8fdc2b218e979cfe422b139b8f74c12419d1f",
              "versionType": "git"
            },
            {
              "lessThan": "a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658",
              "status": "affected",
              "version": "2a437b86ac5a9893c902f30ef66815bf13587bf6",
              "versionType": "git"
            },
            {
              "lessThan": "a7eb6db1cd3f7b556a301dc1265945ad112089f7",
              "status": "affected",
              "version": "76c84c3728178b2d38d5604e399dfe8b0752645e",
              "versionType": "git"
            },
            {
              "lessThan": "834cbca3b12e46887f7a9b35f1981a888360ea4c",
              "status": "affected",
              "version": "cc55dd28c20a6611e30596019b3b2f636819a4c0",
              "versionType": "git"
            },
            {
              "lessThan": "19b1994069dd29478ba767de1f98f14a088198dc",
              "status": "affected",
              "version": "c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7",
              "versionType": "git"
            },
            {
              "lessThan": "fc9f5ee1b073bd233d9c604e338af4ebb42cbc33",
              "status": "affected",
              "version": "c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7",
              "versionType": "git"
            },
            {
              "lessThan": "749179c2e25b95d22499ed29096b3e02d6dfd2b4",
              "status": "affected",
              "version": "c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "8f1c022541bf5a923c8d6fa483112c15250f30a4",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c4e8a172501e677ebd8ea9d9161d97dc4df56fbd",
              "versionType": "git"
            },
            {
              "lessThan": "5.10.265",
              "status": "affected",
              "version": "5.10.238",
              "versionType": "semver"
            },
            {
              "lessThan": "5.15.216",
              "status": "affected",
              "version": "5.15.185",
              "versionType": "semver"
            },
            {
              "lessThan": "6.1.183",
              "status": "affected",
              "version": "6.1.141",
              "versionType": "semver"
            },
            {
              "lessThan": "6.6.148",
              "status": "affected",
              "version": "6.6.93",
              "versionType": "semver"
            },
            {
              "lessThan": "6.12.101",
              "status": "affected",
              "version": "6.12.31",
              "versionType": "semver"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.294",
              "versionType": "semver"
            },
            {
              "lessThan": "6.15",
              "status": "affected",
              "version": "6.14.9",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/can/bcm.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": "5.10.*",
              "status": "unaffected",
              "version": "5.10.265",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.216",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.183",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.148",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.101",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.265",
                  "versionStartIncluding": "5.10.238",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.216",
                  "versionStartIncluding": "5.15.185",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.183",
                  "versionStartIncluding": "6.1.141",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.148",
                  "versionStartIncluding": "6.6.93",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.101",
                  "versionStartIncluding": "6.12.31",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.42",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.4.294",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.14.9",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: bcm: add locking when updating filter and timer values\n\nKCSAN detected a simultaneous access to timer values that can be\noverwritten in bcm_rx_setup() when updating timer and filter content\nwhile bcm_rx_handler(), bcm_rx_timeout_handler() or bcm_rx_thr_handler()\nrun concurrently on incoming CAN traffic.\n\nProtect the timer (ival1/ival2/kt_ival1/kt_ival2/kt_lastmsg) and filter\n(nframes/flags/frames/last_frames) updates in bcm_rx_setup() with a new\nper-op bcm_rx_update_lock, taken with the matching scope in the RX\nhandlers. memcpy_from_msg() is staged into a temporary buffer before the\nlock is taken, since it can sleep and must not run under a spinlock.\n\nhrtimer_cancel() is always called without bcm_rx_update_lock held, since\nbcm_rx_timeout_handler()/bcm_rx_thr_handler() take the same lock and a\nrunning callback would otherwise deadlock against the canceller.\n\nAlso close a related race: bcm_rx_setup() cleared the RTR flag in the\nstored reply frame\u0027s can_id as a separate, unprotected step after the\nframe content was already installed, so a concurrent bcm_rx_handler()\ncould transmit a stale reply with CAN_RTR_FLAG still set. Fold that\nnormalization into the initial frame preparation instead (on the staged\nbuffer for updates, directly on op-\u003eframes pre-registration for new\nops), so the installed frame is always atomically self-consistent.\n\nbcm_rx_handler()\u0027s RX_RTR_FRAME check now takes a lock-protected\nsnapshot of op-\u003eflags before deciding whether to call bcm_can_tx(),\nbut does not hold the lock across that call.\n\nAlso take a lock-protected snapshot of the currframe in bcm_can_tx()\nto avoid partly overwrites by content updates in bcm_tx_setup().\nFinally check if a TX_RESET_MULTI_IDX/SETTIMER might have reset\nop-\u003ecurrframe between the two locked sections in bcm_can_tx().\n\nOmit calling hrtimer_forward() with zero interval in bcm_rx_thr_handler().\nkt_ival2 may have been concurrently cleared by bcm_rx_setup() before it\ncancels this timer, so check kt_ival2 inside the bcm_rx_update_lock."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - The race is driven by concurrent CAN frame reception in bcm_rx_handler()/timer callbacks on a shared CAN segment (automotive OBD/ECU bus, factory controllers, CAN-USB adapters), an adjacent broadcast medium comparable to Bluetooth/WiFi segment access.\nAC:L - An attacker controls both race sides by flooding RX_SETUP via sendmsg while concurrently injecting matching CAN frames or armed timers; syzbot reliably reproduced the KCSAN race without timing conditions beyond attacker control.\nPR:N - CAN_BCM sockets impose no capability checks in can_create()/bcm_sendmsg(), and a bus participant can trigger the RX handler path without any Linux credentials while racing BCM configuration updates from local services.\nUI:N - Exploitation requires no victim interaction beyond normal background CAN/BCM activity on systems that already use the Broadcast Manager for monitoring or diagnostics.\nS:U - Impact is confined to kernel memory corruption and privilege boundaries within the same host; this is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.\nC:H - Unlocked concurrent updates to nframes/flags/frames/last_frames permit torn reads and out-of-bounds accesses in handler loops and timeout memset, matching the prior BCM race class that produced KASAN slab-out-of-bounds reads.\nI:H - Partial overwrites of op-\u003eframes during bcm_can_tx(), stale RTR replies transmitted on the bus, and size-mismatched memset/memcpy against concurrently shrinking buffers enable arbitrary CAN injection and kernel heap corruption.\nA:H - Concurrent timer corruption (hrtimer_forward with zero kt_ival2), torn structure fields, and heap corruption from racing memset/copy operations can cause kernel oops, panic, or sustained denial of service on CAN-equipped systems."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-19T16:36:16.520Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/96994180bd7b248b0cc698afe926e23fc1bda59b"
        },
        {
          "url": "https://git.kernel.org/stable/c/caa8704a7f3cb7806331596195385437126ecb3a"
        },
        {
          "url": "https://git.kernel.org/stable/c/a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658"
        },
        {
          "url": "https://git.kernel.org/stable/c/a7eb6db1cd3f7b556a301dc1265945ad112089f7"
        },
        {
          "url": "https://git.kernel.org/stable/c/834cbca3b12e46887f7a9b35f1981a888360ea4c"
        },
        {
          "url": "https://git.kernel.org/stable/c/19b1994069dd29478ba767de1f98f14a088198dc"
        },
        {
          "url": "https://git.kernel.org/stable/c/fc9f5ee1b073bd233d9c604e338af4ebb42cbc33"
        },
        {
          "url": "https://git.kernel.org/stable/c/749179c2e25b95d22499ed29096b3e02d6dfd2b4"
        }
      ],
      "title": "can: bcm: add locking when updating filter and timer values",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72121",
    "datePublished": "2026-08-15T05:52:59.959Z",
    "dateReserved": "2026-08-09T03:40:39.907Z",
    "dateUpdated": "2026-08-19T16:36:16.520Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-72121",
      "date": "2026-09-21",
      "epss": "0.00345",
      "percentile": "0.27998"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "net/can/bcm.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "96994180bd7b248b0cc698afe926e23fc1bda59b",
                    "status": "affected",
                    "version": "7595de7bc56e0e52b74e56c90f7e247bf626d628",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "caa8704a7f3cb7806331596195385437126ecb3a",
                    "status": "affected",
                    "version": "fbd8fdc2b218e979cfe422b139b8f74c12419d1f",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658",
                    "status": "affected",
                    "version": "2a437b86ac5a9893c902f30ef66815bf13587bf6",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "a7eb6db1cd3f7b556a301dc1265945ad112089f7",
                    "status": "affected",
                    "version": "76c84c3728178b2d38d5604e399dfe8b0752645e",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "834cbca3b12e46887f7a9b35f1981a888360ea4c",
                    "status": "affected",
                    "version": "cc55dd28c20a6611e30596019b3b2f636819a4c0",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "19b1994069dd29478ba767de1f98f14a088198dc",
                    "status": "affected",
                    "version": "c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "fc9f5ee1b073bd233d9c604e338af4ebb42cbc33",
                    "status": "affected",
                    "version": "c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "749179c2e25b95d22499ed29096b3e02d6dfd2b4",
                    "status": "affected",
                    "version": "c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7",
                    "versionType": "git"
                  },
                  {
                    "status": "affected",
                    "version": "8f1c022541bf5a923c8d6fa483112c15250f30a4",
                    "versionType": "git"
                  },
                  {
                    "status": "affected",
                    "version": "c4e8a172501e677ebd8ea9d9161d97dc4df56fbd",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "5.10.265",
                    "status": "affected",
                    "version": "5.10.238",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "5.15.216",
                    "status": "affected",
                    "version": "5.15.185",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "6.1.183",
                    "status": "affected",
                    "version": "6.1.141",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "6.6.148",
                    "status": "affected",
                    "version": "6.6.93",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "6.12.101",
                    "status": "affected",
                    "version": "6.12.31",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "5.5",
                    "status": "affected",
                    "version": "5.4.294",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "6.15",
                    "status": "affected",
                    "version": "6.14.9",
                    "versionType": "semver"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "net/can/bcm.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": "5.10.*",
                    "status": "unaffected",
                    "version": "5.10.265",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "5.15.*",
                    "status": "unaffected",
                    "version": "5.15.216",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.1.*",
                    "status": "unaffected",
                    "version": "6.1.183",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.6.*",
                    "status": "unaffected",
                    "version": "6.6.148",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.12.*",
                    "status": "unaffected",
                    "version": "6.12.101",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.18.*",
                    "status": "unaffected",
                    "version": "6.18.42",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "7.1.*",
                    "status": "unaffected",
                    "version": "7.1.5",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.2",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: bcm: add locking when updating filter and timer values\n\nKCSAN detected a simultaneous access to timer values that can be\noverwritten in bcm_rx_setup() when updating timer and filter content\nwhile bcm_rx_handler(), bcm_rx_timeout_handler() or bcm_rx_thr_handler()\nrun concurrently on incoming CAN traffic.\n\nProtect the timer (ival1/ival2/kt_ival1/kt_ival2/kt_lastmsg) and filter\n(nframes/flags/frames/last_frames) updates in bcm_rx_setup() with a new\nper-op bcm_rx_update_lock, taken with the matching scope in the RX\nhandlers. memcpy_from_msg() is staged into a temporary buffer before the\nlock is taken, since it can sleep and must not run under a spinlock.\n\nhrtimer_cancel() is always called without bcm_rx_update_lock held, since\nbcm_rx_timeout_handler()/bcm_rx_thr_handler() take the same lock and a\nrunning callback would otherwise deadlock against the canceller.\n\nAlso close a related race: bcm_rx_setup() cleared the RTR flag in the\nstored reply frame\u0027s can_id as a separate, unprotected step after the\nframe content was already installed, so a concurrent bcm_rx_handler()\ncould transmit a stale reply with CAN_RTR_FLAG still set. Fold that\nnormalization into the initial frame preparation instead (on the staged\nbuffer for updates, directly on op-\u003eframes pre-registration for new\nops), so the installed frame is always atomically self-consistent.\n\nbcm_rx_handler()\u0027s RX_RTR_FRAME check now takes a lock-protected\nsnapshot of op-\u003eflags before deciding whether to call bcm_can_tx(),\nbut does not hold the lock across that call.\n\nAlso take a lock-protected snapshot of the currframe in bcm_can_tx()\nto avoid partly overwrites by content updates in bcm_tx_setup().\nFinally check if a TX_RESET_MULTI_IDX/SETTIMER might have reset\nop-\u003ecurrframe between the two locked sections in bcm_can_tx().\n\nOmit calling hrtimer_forward() with zero interval in bcm_rx_thr_handler().\nkt_ival2 may have been concurrently cleared by bcm_rx_setup() before it\ncancels this timer, so check kt_ival2 inside the bcm_rx_update_lock."
          }
        ],
        "id": "CVE-2026-72121",
        "lastModified": "2026-08-19T17:20:59.160",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "ADJACENT_NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 8.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-08-15T06:21:26.650",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/19b1994069dd29478ba767de1f98f14a088198dc"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/749179c2e25b95d22499ed29096b3e02d6dfd2b4"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/834cbca3b12e46887f7a9b35f1981a888360ea4c"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/96994180bd7b248b0cc698afe926e23fc1bda59b"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/a7eb6db1cd3f7b556a301dc1265945ad112089f7"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/caa8704a7f3cb7806331596195385437126ecb3a"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/fc9f5ee1b073bd233d9c604e338af4ebb42cbc33"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-17T22:54:17+00:00",
      "cve": "CVE-2026-72121",
      "id": "CVE-2026-72121",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "62",
      "product_status:known_not_affected": "212",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: can: bcm: add locking when updating filter and timer values",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72121.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T01:29:24Z",
      "cve": "CVE-2026-72121",
      "id": "CVE-2026-72121",
      "initial_release_date": "2026-08-31T13:30:47Z",
      "product_status:known_affected": "362",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72121",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72121.json",
      "version": "4"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • 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.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.