Description
In the Linux kernel, the following vulnerability has been resolved:
can: isotp: serialize TX state transitions under so->rx_lock
The TX state machine (so->tx.state) is driven from three contexts:
sendmsg() claiming and progressing a transfer, the RX path consuming
Flow Control/echo frames, and two hrtimers timing out a stalled
transfer. Mixing a lock-free cmpxchg() claim in sendmsg() with
hrtimer_cancel() calls made under so->rx_lock elsewhere left windows
where a frame or timer callback could act on a state that had already
moved on, corrupting an unrelated transfer.
so->rx_lock now covers the full lifecycle of a TX claim: sendmsg()
takes it to check so->tx.state is ISOTP_IDLE, switch it to
ISOTP_SENDING, bump so->tx_gen and drain the previous transfer's
timers - all as one critical section. isotp_rcv_fc()/isotp_rcv_cf()
already run under this lock via isotp_rcv(), and isotp_rcv_echo() now
takes it itself, so none of them can ever observe a transfer mid-claim.
This also means a transfer can no longer be handed to sendmsg()'s
cleanup paths (signal or send error) while another thread is
concurrently claiming or finishing it, so those paths can cancel
timers and reset the state unconditionally.
isotp_release() claims the socket the same way, so a racing sendmsg()
sees a consistent ISOTP_SHUTDOWN and skips arming its timer or sending.
Only the hrtimer callbacks stay outside so->rx_lock, since they run
under so->rx_lock's cancellation elsewhere and taking it themselves
would deadlock. so->tx_gen lets them recognize whether the transfer
they timed out is still the one currently active, so they don't
report an error against a transfer that has since completed or been
superseded.
can: isotp: serialize TX state transitions under so->rx_lock
The TX state machine (so->tx.state) is driven from three contexts:
sendmsg() claiming and progressing a transfer, the RX path consuming
Flow Control/echo frames, and two hrtimers timing out a stalled
transfer. Mixing a lock-free cmpxchg() claim in sendmsg() with
hrtimer_cancel() calls made under so->rx_lock elsewhere left windows
where a frame or timer callback could act on a state that had already
moved on, corrupting an unrelated transfer.
so->rx_lock now covers the full lifecycle of a TX claim: sendmsg()
takes it to check so->tx.state is ISOTP_IDLE, switch it to
ISOTP_SENDING, bump so->tx_gen and drain the previous transfer's
timers - all as one critical section. isotp_rcv_fc()/isotp_rcv_cf()
already run under this lock via isotp_rcv(), and isotp_rcv_echo() now
takes it itself, so none of them can ever observe a transfer mid-claim.
This also means a transfer can no longer be handed to sendmsg()'s
cleanup paths (signal or send error) while another thread is
concurrently claiming or finishing it, so those paths can cancel
timers and reset the state unconditionally.
isotp_release() claims the socket the same way, so a racing sendmsg()
sees a consistent ISOTP_SHUTDOWN and skips arming its timer or sending.
Only the hrtimer callbacks stay outside so->rx_lock, since they run
under so->rx_lock's cancellation elsewhere and taking it themselves
would deadlock. so->tx_gen lets them recognize whether the transfer
they timed out is still the one currently active, so they don't
report an error against a transfer that has since completed or been
superseded.
Published:
2026-08-15
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data available yet.
Remediation
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Advisories
No advisories yet.
References
History
Sat, 15 Aug 2026 06:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: can: isotp: serialize TX state transitions under so->rx_lock The TX state machine (so->tx.state) is driven from three contexts: sendmsg() claiming and progressing a transfer, the RX path consuming Flow Control/echo frames, and two hrtimers timing out a stalled transfer. Mixing a lock-free cmpxchg() claim in sendmsg() with hrtimer_cancel() calls made under so->rx_lock elsewhere left windows where a frame or timer callback could act on a state that had already moved on, corrupting an unrelated transfer. so->rx_lock now covers the full lifecycle of a TX claim: sendmsg() takes it to check so->tx.state is ISOTP_IDLE, switch it to ISOTP_SENDING, bump so->tx_gen and drain the previous transfer's timers - all as one critical section. isotp_rcv_fc()/isotp_rcv_cf() already run under this lock via isotp_rcv(), and isotp_rcv_echo() now takes it itself, so none of them can ever observe a transfer mid-claim. This also means a transfer can no longer be handed to sendmsg()'s cleanup paths (signal or send error) while another thread is concurrently claiming or finishing it, so those paths can cancel timers and reset the state unconditionally. isotp_release() claims the socket the same way, so a racing sendmsg() sees a consistent ISOTP_SHUTDOWN and skips arming its timer or sending. Only the hrtimer callbacks stay outside so->rx_lock, since they run under so->rx_lock's cancellation elsewhere and taking it themselves would deadlock. so->tx_gen lets them recognize whether the transfer they timed out is still the one currently active, so they don't report an error against a transfer that has since completed or been superseded. | |
| Title | can: isotp: serialize TX state transitions under so->rx_lock | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-15T05:53:02.172Z
Reserved: 2026-08-09T03:40:39.907Z
Link: CVE-2026-72124
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-15T06:21:29.720
Modified: 2026-08-15T06:21:29.720
Link: CVE-2026-72124
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.