cifs: Fix uninitialized memory read for smb311 posix symlink create

stable inclusion
from stable-v4.19.270
commit 707682dbab5b61d6b7a95b05491b476510aeeb64
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6DPF8


CVE: NA

--------------------------------

commit a152d05a upstream.

If smb311 posix is enabled, we send the intended mode for file
creation in the posix create context. Instead of using what's there on
the stack, create the mfsymlink file with 0644.

Fixes: ce558b0e ("smb3: Add posix create context for smb3.11 posix mounts")
Cc: stable@vger.kernel.org
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Tom Talpey <tom@talpey.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>