Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+3ef5c0d1a5cb0b21e6be@syzkaller.appspotmail.com, Amir Goldstein , Miklos Szeredi Subject: [PATCH 4.14 034/124] ovl: fix recursive oi->lock in ovl_link() Date: Mon, 19 Nov 2018 17:28:08 +0100 Message-Id: <20181119162620.202267396@linuxfoundation.org> In-Reply-To: <20181119162612.951907286@linuxfoundation.org> References: <20181119162612.951907286@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Amir Goldstein commit 6cd078702f2f33cb6b19a682de3e9184112f1a46 upstream. linking a non-copied-up file into a non-copied-up parent results in a nested call to mutex_lock_interruptible(&oi->lock). Fix this by copying up target parent before ovl_nlink_start(), same as done in ovl_rename(). ~/unionmount-testsuite$ ./run --ov -s ~/unionmount-testsuite$ ln /mnt/a/foo100 /mnt/a/dir100/ WARNING: possible recursive locking detected -------------------------------------------- ln/1545 is trying to acquire lock: 00000000bcce7c4c (&ovl_i_lock_key[depth]){+.+.}, at: ovl_copy_up_start+0x28/0x7d but task is already holding lock: 0000000026d73d5b (&ovl_i_lock_key[depth]){+.+.}, at: ovl_nlink_start+0x3c/0xc1 [SzM: this seems to be a false positive, but doing the copy-up first is harmless and removes the lockdep splat] Reported-by: syzbot+3ef5c0d1a5cb0b21e6be@syzkaller.appspotmail.com Fixes: 5f8415d6b87e ("ovl: persistent overlay inode nlink for...") Cc: # v4.13 Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi [amir: backport to v4.18] Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/dir.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -595,6 +595,11 @@ static int ovl_link(struct dentry *old, if (err) goto out_drop_write; + err = ovl_copy_up(new->d_parent); + if (err) + goto out_drop_write; + + err = ovl_nlink_start(old, &locked); if (err) goto out_drop_write;