can: bcm: defer rx_op deallocation to workqueue to fix thrtimer UAF
In the Linux kernel, the following vulnerability has been resolved: can: bcm: defer rx_op deallocation to workqueue to fix thrtimer UAF Commit f1b4e32aca08 ("can: bcm: use call_rcu() instead of costly synchronize_rcu()") replaced synchronize_rcu() in bcm_delete_rx_op() with call_rcu() and introduced the RX_NO_AUTOTIMER flag. However, this flag check was omitted for thrtimer in the packet rx fast-path. During BCM RX operation teardown, a concurrent RCU reader (bcm_rx_handler) can race and re-arm thrtimer via bcm_rx_update_and_send() after call_rcu() has been scheduled. Once the RCU grace period elapses, bcm_op is freed. The subsequently firing thrtimer then dereferences the deallocated op, causing a UAF. Adding flag checks to the rx fast-path (bcm_rx_update_and_send) does not fully close the TOCTOU race and introduces latency for every CAN frame. Conversely, calling hrtimer_cancel() directly inside the RCU callback (softirq context) is fatal as hrtimer_cancel() can sleep, triggering a "scheduling while atomic" panic. Resolve this by deferring the timer cancellation and memory free to a dedicated unbound workqueue (bcm_wq). The RCU callback now queues a work item to bcm_wq, which safely cancels both timers and deallocates memory in sleepable process context. A dedicated workqueue is used to prevent system-wide WQ saturation and is cleanly flushed/destroyed on module unload to avoid rmmod page faults. Since the deferred work can now outlive the calling context by an unbounded am
CVE-2026-72123
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-72123
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "85cd41070df992d3c0dfd828866fdd243d3b774a",
"lessThan": "de5fce46637de05bef56ec08528127676eb6fc9b",
"versionType": "git"
},
{
"status": "affected",
"version": "f34f2a18e47b73e48f90a757e1f4aaa8c7d665a1",
"lessThan": "036a8c320ca11bc912e8027adcfad14b326f067e",
"versionType": "git"
},
{
"status": "affected",
"version": "f1b4e32aca0811aa011c76e5d6cf2fa19224b386",
"lessThan": "3cf4fd5316f449811d8baf1bc6978ef5a7b743a9",
"versionType": "git"
},
{
"status": "affected",
"version": "f1b4e32aca0811aa011c76e5d6cf2fa19224b386",
"lessThan": "4177762f70646ac48a2af382e45a795cbd295198",
"versionType": "git"
},
{
"status": "affected",
"version": "f1b4e32aca0811aa011c76e5d6cf2fa19224b386",
"lessThan": "6fd08e8d826c3aa4cc7021f5f9cdbb7fa7441d3f",
"versionType": "git"
},
{
"status": "affected",
"version": "f1b4e32aca0811aa011c76e5d6cf2fa19224b386",
"lessThan": "cd830e0bc25ee2d38cbfbdbb3cd77c5f53b2b6d5",
"versionType": "git"
},
{
"status": "affected",
"version": "f1b4e32aca0811aa011c76e5d6cf2fa19224b386",
"lessThan": "ce2d4b121fb7545e1ed588e860c8e5fd5ad45224",
"versionType": "git"
},
{
"status": "affected",
"version": "f1b4e32aca0811aa011c76e5d6cf2fa19224b386",
"lessThan": "68973f9db76144825e4f35dfdc80fb8279eb2d57",
"versionType": "git"
},
{
"status": "affected",
"version": "fbac09a3b8890003c0c55294c00709f3ae5501bb",
"versionType": "git"
},
{
"status": "affected",
"version": "5b48f5711f1c630841ab78dcc061de902f0e37bf",
"versionType": "git"
},
{
"status": "affected",
"version": "edb4baffb9483141a50fb7f7146cfe4a4c0c2db8",
"versionType": "git"
},
{
"status": "affected",
"version": "5.10.130",
"lessThan": "5.10.265",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.15.54",
"lessThan": "5.15.216",
"versionType": "semver"
},
{
"status": "affected",
"version": "4.19.252",
"lessThan": "4.20",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.4.205",
"lessThan": "5.5",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.18.11",
"lessThan": "5.19",
"versionType": "semver"
}
],
"programFiles": [
"net/can/bcm.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.19"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.19",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/can/bcm.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-72123
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #32950 · Revision 1
- Added to Heist Feed
- Publisher date