rxrpc: Fix call timer start racing with call destruction

Summary

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix call timer start racing with call destruction The rxrpc_call struct has a timer used to handle various timed events relating to a call. This timer can get started from the packet input routines that are run in softirq mode with just the RCU read lock held. Unfortunately, because only the RCU read lock is held - and neither ref or other lock is taken - the call can start getting destroyed at the same time a packet comes in addressed to that call. This causes the timer - which was already stopped - to get restarted. Later, the timer dispatch code may then oops if the timer got deallocated first. Fix this by trying to take a ref on the rxrpc_call struct and, if successful, passing that ref along to the timer. If the timer was already running, the ref is discarded. The timer completion routine can then pass the ref along to the call's work item when it queues it. If the timer or work item where already queued/running, the extra ref is discarded.

Timeline

1. Feb 26, 2025, 1:55 AM UTCCVE published
2. Oct 15, 2026, 9:17 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: total

3. Oct 15, 2026, 9:21 PM UTCRecord last updated

Affected versions

• Linux Linux

  From a158bdd3247b9656df36ba133235fff702e9fdc3 · fixed in 051360e51341cd17738d82c15a8226010c7cb7f6; From a158bdd3247b9656df36ba133235fff702e9fdc3 · fixed in 8cbf4ae7a2833767d63114573e5f9a45740cc975; From a158bdd3247b9656df36ba133235fff702e9fdc3 · fixed in 54df5a37f1d951ed27fd47bf9b15a42279582110; From a158bdd3247b9656df36ba133235fff702e9fdc3 · fixed in 5e3c11144e557a9dbf9a2f6abe444689ef9d8aae; From a158bdd3247b9656df36ba133235fff702e9fdc3 · fixed in 4a7f62f91933c8ae5308f9127fd8ea48188b6bc3

• Linux Linux

  4.15

• KernelLinux

  From 4.15.0 · fixed in 5.10.110; From 5.11.0 · fixed in 5.15.33; From 5.16.0 · fixed in 5.16.19; From 5.17.0 · fixed in 5.17.2

References 5