tree dbe0c6586fee9041e6b97e0a24432f89171409cd
parent 12a5ba5a1994568d4ceaff9e78c6b0329d953386
author Michal Kubecek <mkubecek@suse.cz> 1584748010 +0100
committer David S. Miller <davem@davemloft.net> 1585023560 -0700

netlink: check for null extack in cookie helpers

Unlike NL_SET_ERR_* macros, nl_set_extack_cookie_u64() and
nl_set_extack_cookie_u32() helpers do not check extack argument for null
and neither do their callers, as syzbot recently discovered for
ethnl_parse_header().

Instead of fixing the callers and leaving the trap in place, add check of
null extack to both helpers to make them consistent with NL_SET_ERR_*
macros.

v2: drop incorrect second Fixes tag

Fixes: 2363d73a2f3e ("ethtool: reject unrecognized request flags")
Reported-by: syzbot+258a9089477493cea67b@syzkaller.appspotmail.com
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>