CVE-2026-31474

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

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

isotpsendmsg() uses only cmpxchg() on so->tx.state to serialize access to so->tx.buf. isotprelease() waits for ISOTPIDLE via waitevent_interruptible() and then calls kfree(so->tx.buf).

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

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 skdestruct time when either isotpsendmsg() and isotp_release() are done.