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keys: Fix request_key() cache
commit 8379bb84be757d5df2d818509faec5d66adb861d upstream.
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: 7743c48e54
("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
6410050a09
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@ -175,8 +175,8 @@ void exit_creds(struct task_struct *tsk)
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put_cred(cred);
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#ifdef CONFIG_KEYS_REQUEST_CACHE
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key_put(current->cached_requested_key);
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current->cached_requested_key = NULL;
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key_put(tsk->cached_requested_key);
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tsk->cached_requested_key = NULL;
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#endif
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}
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