netlink: Use netlink header as base to calculate bad attribute offset

[ Upstream commit 84b3268027641401bb8ad4427a90a3cce2eb86f5 ]

Userspace might send a batch that is composed of several netlink
messages. The netlink_ack() function must use the pointer to the netlink
header as base to calculate the bad attribute offset.

Fixes: 2d4bc93368 ("netlink: extended ACK reporting")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pablo Neira Ayuso 2020-02-26 19:47:34 +01:00 committed by Greg Kroah-Hartman
parent 53e404eddd
commit 7aa760f0f5

View File

@ -2411,7 +2411,7 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
in_skb->len))
WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
(u8 *)extack->bad_attr -
in_skb->data));
(u8 *)nlh));
} else {
if (extack->cookie_len)
WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,