smack: fix cred UAF in smack_file_send_sigiotask()

Summary

In the Linux kernel, the following vulnerability has been resolved: smack: fix cred UAF in smack_file_send_sigiotask() When inspecting the credentials of another task, objective credentials (->real_cred, accessed with __task_cred()) must always be used. Accessing ->cred on a non-current task is forbidden unless that task is being created or destroyed; a task is allowed to change its own ->cred pointer with no synchronization, and changing ->cred should only affect the current syscall. smack_file_send_sigiotask() was accessing both sets of credentials: First tsk->cred, then __task_cred(tsk). Fix it, always access the objective credentials here. I have tested that this bug can lead to a KASAN-reported UAF of struct cred in smack_file_send_sigiotask(), and that this fix prevents the race.

Timeline

1. Sep 11, 2026, 7:42 PM UTCCVE published
2. Oct 19, 2026, 8:45 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 3b11a1decef07c19443d24ae926982bc8ec9f4c0 · fixed in a512366d84e134a9eefc2cc40eeb6e80e2ec162c; From 3b11a1decef07c19443d24ae926982bc8ec9f4c0 · fixed in 7c7fe043f3099d0d35002b248967f75e55345b93; From 3b11a1decef07c19443d24ae926982bc8ec9f4c0 · fixed in f9c7b1f2b9d8f4176d2632743f51400855978ace; From 3b11a1decef07c19443d24ae926982bc8ec9f4c0 · fixed in b5bcf3adfa27279da4401ab8f1e1a706601a92be; From 3b11a1decef07c19443d24ae926982bc8ec9f4c0 · fixed in ed64aa505875a3b4defd504ee8e59e1949246a62; From 3b11a1decef07c19443d24ae926982bc8ec9f4c0 · fixed in b791401bf389a1546a830d2b381ca60fe94c7870; From 3b11a1decef07c19443d24ae926982bc8ec9f4c0 · fixed in fedc88e38ce979a720cd2de042578cb5df3dc8de

• Linux Linux

  2.6.29

• KernelLinux

  From 2.6.29 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.109; From 6.13.0 · fixed in 6.18.50; From 6.19.0 · fixed in 7.2.4

References 7