CVE-2026-72121can: bcm: add locking when updating filter and timer values

Description

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.

Timeline

Scores

EPSS (exploitation in 30 days)

0.35% · top 70% of all CVEs (14 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.8.

Affected products

• Linux · Linux

  • affected 7595de7bc56e0e52b74e56c90f7e247bf626d628 – < 96994180bd7b248b0cc698afe926e23fc1bda59b
  • affected fbd8fdc2b218e979cfe422b139b8f74c12419d1f – < caa8704a7f3cb7806331596195385437126ecb3a
  • affected 2a437b86ac5a9893c902f30ef66815bf13587bf6 – < a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658
  • affected 76c84c3728178b2d38d5604e399dfe8b0752645e – < a7eb6db1cd3f7b556a301dc1265945ad112089f7
  • affected cc55dd28c20a6611e30596019b3b2f636819a4c0 – < 834cbca3b12e46887f7a9b35f1981a888360ea4c
  • affected c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7 – < 19b1994069dd29478ba767de1f98f14a088198dc
  • affected c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7 – < fc9f5ee1b073bd233d9c604e338af4ebb42cbc33
  • affected c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7 – < 749179c2e25b95d22499ed29096b3e02d6dfd2b4
  • affected 8f1c022541bf5a923c8d6fa483112c15250f30a4
  • affected c4e8a172501e677ebd8ea9d9161d97dc4df56fbd
  • affected 5.10.238 – < 5.10.265
  • affected 5.15.185 – < 5.15.216
  • affected 6.1.141 – < 6.1.183
  • affected 6.6.93 – < 6.6.148
  • affected 6.12.31 – < 6.12.101
  • affected 5.4.294 – < 5.5
  • affected 6.14.9 – < 6.15

• Linux · Linux

  • affected 6.15
  • unaffected < 6.15
  • unaffected 5.10.265 – ≤ 5.10.*
  • unaffected 5.15.216 – ≤ 5.15.*
  • unaffected 6.1.183 – ≤ 6.1.*
  • unaffected 6.6.148 – ≤ 6.6.*
  • unaffected 6.12.101 – ≤ 6.12.*
  • unaffected 6.18.42 – ≤ 6.18.*
  • unaffected 7.1.5 – ≤ 7.1.*
  • unaffected 7.2 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-58879 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-72121](https://cveledger.app/badge/CVE-2026-72121.svg)](https://cveledger.app/cve/CVE-2026-72121)

Record last updated 16 Oct 2026, 18:44 UTC.