tree 4a5c150198cfdde4c07e4cfe55995c5cd51830df
parent 219d54332a09e8d8741c1e1982f5eae56099de85
author David Howells <dhowells@redhat.com> 1579017974 +0000
committer Linus Torvalds <torvalds@linux-foundation.org> 1579023606 -0800

keys: Fix request_key() cache

When the key cached by request_key() and co.  is cleaned up on exit(),
the code looks in the wrong task_struct, and so clears the wrong cache.
This leads to anomalies in key refcounting when doing, say, a kernel
build on an afs volume, that then trigger kasan to report a
use-after-free when the key is viewed in /proc/keys.

Fix this by making exit_creds() look in the passed-in task_struct rather
than in current (the task_struct cleanup code is deferred by RCU and
potentially run in another task).

Fixes: 7743c48e54ee ("keys: Cache result of request_key*() temporarily in task_struct")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>