fix regression in "epoll: Keep a reference on files added to the chec…

…k 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. Bug: 147802478 Tested-by: Marc Zyngier <[email protected]> Fixes: a9ed4a6560b8 ("epoll: Keep a reference on files added to the check list") Signed-off-by: Al Viro <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Change-Id: I541299a6325a6e9765add9e920cfa0203de9f4a0 Signed-off-by: engstk <[email protected]>
engstk · Nov 3, 2020 · 09be51f · 09be51f
1 parent 8b9bd8e
commit 09be51f
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
@@ -1911,9 +1911,9 @@ 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);
 			}
 		}
 	}