CVE-2026-72121: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-85wx-h4w2-c465",
  "modified" : "2026-08-19T18:32:27Z",
  "published" : "2026-08-15T06:32:12Z",
  "aliases" : [ "CVE-2026-72121" ],
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-72121"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/19b1994069dd29478ba767de1f98f14a088198dc"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/749179c2e25b95d22499ed29096b3e02d6dfd2b4"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/834cbca3b12e46887f7a9b35f1981a888360ea4c"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/96994180bd7b248b0cc698afe926e23fc1bda59b"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/a7eb6db1cd3f7b556a301dc1265945ad112089f7"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/caa8704a7f3cb7806331596195385437126ecb3a"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/fc9f5ee1b073bd233d9c604e338af4ebb42cbc33"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-15T06:21:26Z"
  }
}