{"id":"CVE-2026-72121","revision":"53342bb216e94f22a1626ef3d69116d6","records":[{"revision":"53342bb216e94f22a1626ef3d69116d6","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-72121","aliases":[],"title":"can: bcm: add locking when updating filter and timer values","description":"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's 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->frames pre-registration for new\nops), so the installed frame is always atomically self-consistent.\n\nbcm_rx_handler()'s RX_RTR_FRAME check now takes a lock-protected\nsnapshot of op->flags 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->currframe 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.","state":0,"publishedAt":"2026-08-15T05:52:59.959+00:00","modifiedAt":"2026-10-16T18:44:57.29+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/can/bcm.c\"\n ],\n \"versions\": [\n {\n \"version\": \"7595de7bc56e0e52b74e56c90f7e247bf626d628\",\n \"lessThan\": \"96994180bd7b248b0cc698afe926e23fc1bda59b\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"fbd8fdc2b218e979cfe422b139b8f74c12419d1f\",\n \"lessThan\": \"caa8704a7f3cb7806331596195385437126ecb3a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2a437b86ac5a9893c902f30ef66815bf13587bf6\",\n \"lessThan\": \"a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"76c84c3728178b2d38d5604e399dfe8b0752645e\",\n \"lessThan\": \"a7eb6db1cd3f7b556a301dc1265945ad112089f7\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"cc55dd28c20a6611e30596019b3b2f636819a4c0\",\n \"lessThan\": \"834cbca3b12e46887f7a9b35f1981a888360ea4c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7\",\n \"lessThan\": \"19b1994069dd29478ba767de1f98f14a088198dc\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7\",\n \"lessThan\": \"fc9f5ee1b073bd233d9c604e338af4ebb42cbc33\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7\",\n \"lessThan\": \"749179c2e25b95d22499ed29096b3e02d6dfd2b4\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"8f1c022541bf5a923c8d6fa483112c15250f30a4\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"c4e8a172501e677ebd8ea9d9161d97dc4df56fbd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"5.10.238\",\n \"lessThan\": \"5.10.265\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.185\",\n \"lessThan\": \"5.15.216\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.141\",\n \"lessThan\": \"6.1.183\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.93\",\n \"lessThan\": \"6.6.148\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.31\",\n \"lessThan\": \"6.12.101\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.4.294\",\n \"lessThan\": \"5.5\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.14.9\",\n \"lessThan\": \"6.15\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/can/bcm.c\"\n ],\n \"versions\": [\n {\n \"version\": \"6.15\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.15\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.265\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.216\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.183\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.148\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.101\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.42\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1.5\",\n \"lessThanOrEqual\": \"7.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/96994180bd7b248b0cc698afe926e23fc1bda59b","https://git.kernel.org/stable/c/caa8704a7f3cb7806331596195385437126ecb3a","https://git.kernel.org/stable/c/a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658","https://git.kernel.org/stable/c/a7eb6db1cd3f7b556a301dc1265945ad112089f7","https://git.kernel.org/stable/c/834cbca3b12e46887f7a9b35f1981a888360ea4c","https://git.kernel.org/stable/c/19b1994069dd29478ba767de1f98f14a088198dc","https://git.kernel.org/stable/c/fc9f5ee1b073bd233d9c604e338af4ebb42cbc33","https://git.kernel.org/stable/c/749179c2e25b95d22499ed29096b3e02d6dfd2b4"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72121","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-72121","identifiers":["CVE-2026-72121"]},"retained":false,"historicalAffected":[]}],"coverage":[]}