CVE-2026-31474

Summary

In the Linux kernel, the following vulnerability has been resolved:

can: isotp: fix tx.buf use-after-free in isotp_sendmsg()

isotp_sendmsg() uses only cmpxchg() on so->tx.state to serialize access to so->tx.buf. isotp_release() waits for ISOTP_IDLE via wait_event_interruptible() and then calls kfree(so->tx.buf).

If a signal interrupts the wait_event_interruptible() inside close() while tx.state is ISOTP_SENDING, the loop exits early and release proceeds to force ISOTP_SHUTDOWN and continues to kfree(so->tx.buf) while sendmsg may still be reading so->tx.buf for the final CAN frame in isotp_fill_dataframe().

The so->tx.buf can be allocated once when the standard tx.buf length needs to be extended. Move the kfree() of this potentially extended tx.buf to sk_destruct time when either isotp_sendmsg() and isotp_release() are done.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux96d1c81e6a0478535342dff6c730adb076cd84e8 < cb3d6efa78460e6d50bf68806d0db66265709f64affected
LinuxLinux96d1c81e6a0478535342dff6c730adb076cd84e8 < 9649d051e54413049c009638ec1dc23962c884a4affected
LinuxLinux96d1c81e6a0478535342dff6c730adb076cd84e8 < eec8a1b18a79600bd4419079dc0026c1db72a830affected
LinuxLinux96d1c81e6a0478535342dff6c730adb076cd84e8 < 2e62e7051eca75a7f2e3d52d62ec10d7d7aa358caffected
LinuxLinux96d1c81e6a0478535342dff6c730adb076cd84e8 < 424e95d62110cdbc8fd12b40918f37e408e35a92affected
LinuxLinux6.4affected
LinuxLinux0 < 6.4unaffected
LinuxLinux6.6.131 <= 6.6.*unaffected
LinuxLinux6.12.80 <= 6.12.*unaffected
LinuxLinux6.18.21 <= 6.18.*unaffected
LinuxLinux6.19.11 <= 6.19.*unaffected
LinuxLinux7.0 <= *unaffected

Weaknesses

ADP Enrichment

kernel: can: isotp: fix tx.buf use-after-free in isotp_sendmsg()

Additional References

References