Bug 2460646 (CVE-2026-31474)

Summary: CVE-2026-31474 kernel: can: isotp: fix tx.buf use-after-free in isotp_sendmsg()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Controller Area Network (CAN) ISO-TP (isotp) module. This vulnerability, known as a use-after-free, occurs when the system attempts to free a memory region while it is still being used. A local attacker could trigger this condition by sending a signal that interrupts a specific waiting process during a close operation. This can lead to memory corruption, potentially causing the system to crash (denial of service) or behave unpredictably.
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Description OSIDB Bzimport 2026-04-22 15:02:52 UTC 
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.
Comment 1 Keith Grant 2026-04-22 18:21:50 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042256-CVE-2026-31474-8673@gregkh/T
Comment 5 errata-xmlrpc 2026-06-19 23:21:49 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:27288 https://access.redhat.com/errata/RHSA-2026:27288
Comment 6 errata-xmlrpc 2026-06-22 05:04:15 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:27731 https://access.redhat.com/errata/RHSA-2026:27731
Comment 7 errata-xmlrpc 2026-06-22 08:28:39 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:27789 https://access.redhat.com/errata/RHSA-2026:27789