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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>

authored by

Fedor Pchelkin and committed by
Steve French
a09dc10d 1aade89e

+2 -2
+2 -2
fs/smb/server/smb2pdu.c
··· 6115 6115 rc = -EINVAL; 6116 6116 ksmbd_debug(SMB, "cannot delete %s\n", 6117 6117 link_name); 6118 - goto out; 6119 6118 } 6120 6119 } else { 6121 6120 rc = -EEXIST; 6122 6121 ksmbd_debug(SMB, "link already exists\n"); 6123 - goto out; 6124 6122 } 6125 6123 ksmbd_vfs_kern_path_end_removing(&path); 6124 + if (rc) 6125 + goto out; 6126 6126 } 6127 6127 rc = ksmbd_vfs_link(work, target_name, link_name); 6128 6128 if (rc)