lkml.org 
[lkml]   [2020]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH] keys: Fix request_key() cache
From
Date
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>
---

kernel/cred.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/cred.c b/kernel/cred.c
index c0a4c12d38b2..56395be1c2a8 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -175,8 +175,8 @@ void exit_creds(struct task_struct *tsk)
put_cred(cred);

#ifdef CONFIG_KEYS_REQUEST_CACHE
- key_put(current->cached_requested_key);
- current->cached_requested_key = NULL;
+ key_put(tsk->cached_requested_key);
+ tsk->cached_requested_key = NULL;
#endif
}

\
 
 \ /
  Last update: 2020-01-14 17:06    [W:0.031 / U:43.312 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site