This is a note to let you know that I've just added the patch titled

netlink: extack needs to be reset each time through loop

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: netlink-extack-needs-to-be-reset-each-time-through-loop.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Sun Jan 28 17:35:08 CET 2018

From: David Ahern dsahern@gmail.com Date: Wed, 10 Jan 2018 13:00:39 -0800 Subject: netlink: extack needs to be reset each time through loop

From: David Ahern dsahern@gmail.com

[ Upstream commit cbbdf8433a5f117b1a2119ea30fc651b61ef7570 ]

syzbot triggered the WARN_ON in netlink_ack testing the bad_attr value. The problem is that netlink_rcv_skb loops over the skb repeatedly invoking the callback and without resetting the extack leaving potentially stale data. Initializing each time through avoids the WARN_ON.

Fixes: 2d4bc93368f5a ("netlink: extended ACK reporting") Reported-by: syzbot+315fa6766d0f7c359327@syzkaller.appspotmail.com Signed-off-by: David Ahern dsahern@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netlink/af_netlink.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2393,7 +2393,7 @@ int netlink_rcv_skb(struct sk_buff *skb, struct nlmsghdr *, struct netlink_ext_ack *)) { - struct netlink_ext_ack extack = {}; + struct netlink_ext_ack extack; struct nlmsghdr *nlh; int err;

@@ -2414,6 +2414,7 @@ int netlink_rcv_skb(struct sk_buff *skb, if (nlh->nlmsg_type < NLMSG_MIN_TYPE) goto ack;

+ memset(&extack, 0, sizeof(extack)); err = cb(skb, nlh, &extack); if (err == -EINTR) goto skip;

Patches currently in stable-queue which might be from dsahern@gmail.com are

queue-4.14/net-ipv4-make-ip-route-get-match-iif-lo-rules-again.patch queue-4.14/net-vrf-add-support-for-sends-to-local-broadcast-address.patch queue-4.14/netlink-extack-needs-to-be-reset-each-time-through-loop.patch queue-4.14/netlink-reset-extack-earlier-in-netlink_rcv_skb.patch