From: Al Viro viro@zeniv.linux.org.uk
stable inclusion from linux-4.19.144 commit 37d933e8b41b83bb8278815e366aec5a542b7e31
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[ 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@kernel.org Fixes: a9ed4a6560b8 ("epoll: Keep a reference on files added to the check list") Signed-off-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- fs/eventpoll.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 6387b6128f3e..76f9079a6802 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1893,9 +1893,9 @@ 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); } } }