ksmbd: fix reference count leak in smb_check_perm_dacl()

[ Upstream commit d21a580dafc69aa04f46e6099616146a536b0724 ]

The issue happens in a specific path in smb_check_perm_dacl(). When
"id" and "uid" have the same value, the function simply jumps out of
the loop without decrementing the reference count of the object
"posix_acls", which is increased by get_acl() earlier. This may
result in memory leaks.

Fix it by decreasing the reference count of "posix_acls" before
jumping to label "check_access_bits".

Fixes: 777cad1604d6 ("ksmbd: remove select FS_POSIX_ACL in Kconfig")
Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/ksmbd/smbacl.c b/fs/ksmbd/smbacl.c
index bd792db..7e57ffd 100644 (file)
--- a/fs/ksmbd/smbacl.c
+++ b/fs/ksmbd/smbacl.c
@@ -1274,6 +1274,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, struct path *path,
                                        if (!access_bits)
                                                access_bits =
                                                        SET_MINIMUM_RIGHTS;
+                                       posix_acl_release(posix_acls);
                                        goto check_access_bits;
                                }
                        }