This is a note to let you know that I've just added the patch titled
fix regression in "epoll: Keep a reference on files added to the check list"
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fix-regression-in-epoll-keep-a-reference-on-files-ad.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 16d858d142afa3a7951940c47c454f7c9076b75f
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Sep 2 11:30:48 2020 -0400
fix regression in "epoll: Keep a reference on files added to the check list"
[ Upstream commit 77f4689de17c0887775bb77896f4cc11a39bf848 ]
epoll_loop_check_proc() can run into a file already committed to destruction;
we can't grab a reference on those and don't need to add them to the set for
reverse path check anyway.
Tested-by: Marc Zyngier <maz@xxxxxxxxxx>
Fixes: a9ed4a6560b8 ("epoll: Keep a reference on files added to the check list")
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 0d9b1e2b9da72..ae1d32344f7ac 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1992,9 +1992,9 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)
* during ep_insert().
*/
if (list_empty(&epi->ffd.file->f_tfile_llink)) {
- get_file(epi->ffd.file);
- list_add(&epi->ffd.file->f_tfile_llink,
- &tfile_check_list);
+ if (get_file_rcu(epi->ffd.file))
+ list_add(&epi->ffd.file->f_tfile_llink,
+ &tfile_check_list);
}
}
}
