ovl_create_temp() treats "workdir" as a parent in which it creates an object so it should use I_MUTEX_PARENT. Prior to the commit identified below the lock was taken by the caller which sometimes used I_MUTEX_PARENT and sometimes used I_MUTEX_NORMAL. The use of I_MUTEX_NORMAL was incorrect but unfortunately copied into ovl_create_temp(). Note to backporters: This patch only applies after the last Fixes given below (post v6.16). To fix the bug in v6.7 and later the inode_lock() call in ovl_copy_up_workdir() needs to nest using I_MUTEX_PARENT. Link: https://lore.kernel.org/all/67a72070.050a0220.3d72c.0022.GAE@xxxxxxxxxx/ Cc: stable@xxxxxxxxxxxxxxx Reported-by: syzbot+7836a68852a10ec3d790@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: c63e56a4a652 ("ovl: do not open/llseek lower file with upper sb_writers held") Fixes: d2c995581c7c ("ovl: Call ovl_create_temp() without lock held.") Signed-off-by: NeilBrown <neil@xxxxxxxxxx> --- 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 70b8687dc45e..dbd63a74df4b 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -225,7 +225,7 @@ struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir, struct ovl_cattr *attr) { struct dentry *ret; - inode_lock(workdir->d_inode); + inode_lock_nested(workdir->d_inode, I_MUTEX_PARENT); ret = ovl_create_real(ofs, workdir, ovl_lookup_temp(ofs, workdir), attr); inode_unlock(workdir->d_inode);
