ksmbd: fix use-after-free in smb2_lock

commit 84d2d1641b71dec326e8736a749b7ee76a9599fc upstream.

If smb_lock->zero_len has value, ->llist of smb_lock is not delete and
flock is old one. It will cause use-after-free on error handling
routine.

Cc: stable@vger.kernel.org
Reported-by: Norbert Szetei <norbert@doyensec.com>
Tested-by: Norbert Szetei <norbert@doyensec.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index c763a2f7df6640b3f73fe4c727897aebfc3891ea..c69be6931e977c3b0404f3d37b62f3927cb7019b 100644 (file)
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -7441,13 +7441,13 @@ out_check_cl:
                }
 
 no_check_cl:
+               flock = smb_lock->fl;
+               list_del(&smb_lock->llist);
+
                if (smb_lock->zero_len) {
                        err = 0;
                        goto skip;
                }
-
-               flock = smb_lock->fl;
-               list_del(&smb_lock->llist);
 retry:
                rc = vfs_lock_file(filp, smb_lock->cmd, flock, NULL);
 skip: