In ovl_rename(), if new upper is hardlinked to old upper underneath
overlayfs before upper dirs are locked, user will get an ESTALE error
and a WARN_ON will be printed.
Changes to underlying layers while overlayfs is mounted may result in
unexpected behavior, but it shouldn't crash the kernel and it shouldn't
trigger WARN_ON() either, so relax this WARN_ON().
Reported-by: syzbot+bb1836a212e69f8e201a@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 804032fabb3b ("ovl: don't check rename to self")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.9+
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/dir.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 702aa63f6774..29abdb1d3b5c 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -1170,7 +1170,7 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
if (newdentry == trap)
goto out_dput;
- if (WARN_ON(olddentry->d_inode == newdentry->d_inode))
+ if (olddentry->d_inode == newdentry->d_inode)
goto out_dput;
err = 0;
--
2.17.1
