ksmbd: call ksmbd_vfs_kern_path_end_removing() on some error paths

There are two places where ksmbd_vfs_kern_path_end_removing() needs to be
called in order to balance what the corresponding successful call to
ksmbd_vfs_kern_path_start_removing() has done, i.e. drop inode locks and
put the taken references.  Otherwise there might be potential deadlocks
and unbalanced locks which are caught like:

BUG: workqueue leaked lock or atomic: kworker/5:21/0x00000000/7596
     last function: handle_ksmbd_work
2 locks held by kworker/5:21/7596:
 #0: ffff8881051ae448 (sb_writers#3){.+.+}-{0:0}, at: ksmbd_vfs_kern_path_locked+0x142/0x660
 #1: ffff888130e966c0 (&type->i_mutex_dir_key#3/1){+.+.}-{4:4}, at: ksmbd_vfs_kern_path_locked+0x17d/0x660
CPU: 5 PID: 7596 Comm: kworker/5:21 Not tainted 6.1.162-00456-gc29b353f383b #138
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
Workqueue: ksmbd-io handle_ksmbd_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x44/0x5b
 process_one_work.cold+0x57/0x5c
 worker_thread+0x82/0x600
 kthread+0x153/0x190
 ret_from_fork+0x22/0x30
 </TASK>

Found by Linux Verification Center (linuxtesting.org).

Fixes: d5fc1400a34b ("smb/server: avoid deadlock when linking with ReplaceIfExists")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index cbb31ef..2782eea 100644 (file)
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -6115,14 +6115,14 @@ static int smb2_create_link(struct ksmbd_work *work,
                                rc = -EINVAL;
                                ksmbd_debug(SMB, "cannot delete %s\n",
                                            link_name);
-                               goto out;
                        }
                } else {
                        rc = -EEXIST;
                        ksmbd_debug(SMB, "link already exists\n");
-                       goto out;
                }
                ksmbd_vfs_kern_path_end_removing(&path);
+               if (rc)
+                       goto out;
        }
        rc = ksmbd_vfs_link(work, target_name, link_name);
        if (rc)