Commit 55b474c4 authored Mar 21, 2020 by Michal Kubecek Committed by David S. Miller Mar 23, 2020

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: 2363d73a ("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>

parent 12a5ba5a

include/linux/netlink.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -115,6 +115,8 @@ static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
		{
		u64 __cookie = cookie;

		if (!extack)
		return;
		memcpy(extack->cookie, &__cookie, sizeof(__cookie));
		extack->cookie_len = sizeof(__cookie);
		}
		@@ -124,6 +126,8 @@ static inline void nl_set_extack_cookie_u32(struct netlink_ext_ack *extack,
		{
		u32 __cookie = cookie;

		if (!extack)
		return;
		memcpy(extack->cookie, &__cookie, sizeof(__cookie));
		extack->cookie_len = sizeof(__cookie);
		}

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