Patch "netlink: reset extack earlier in netlink_rcv_skb" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

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

    netlink: reset extack earlier in netlink_rcv_skb

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netlink-reset-extack-earlier-in-netlink_rcv_skb.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: Xin Long <lucien.xin@gmail.com>
Date: Thu, 18 Jan 2018 14:48:03 +0800
Subject: netlink: reset extack earlier in netlink_rcv_skb

From: Xin Long <lucien.xin@gmail.com>


[ Upstream commit cd443f1e91ca600a092e780e8250cd6a2954b763 ]

Move up the extack reset/initialization in netlink_rcv_skb, so that
those 'goto ack' will not skip it. Otherwise, later on netlink_ack
may use the uninitialized extack and cause kernel crash.

Fixes: cbbdf8433a5f ("netlink: extack needs to be reset each time through loop")
Reported-by: syzbot+03bee3680a37466775e7@syzkaller.appspotmail.com
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-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 |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2400,6 +2400,7 @@ int netlink_rcv_skb(struct sk_buff *skb,
 	while (skb->len >= nlmsg_total_size(0)) {
 		int msglen;
 
+		memset(&extack, 0, sizeof(extack));
 		nlh = nlmsg_hdr(skb);
 		err = 0;
 
@@ -2414,7 +2415,6 @@ 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 lucien.xin@gmail.com are

queue-4.14/sctp-do-not-allow-the-v4-socket-to-bind-a-v4mapped-v6-address.patch
queue-4.14/sctp-reinit-stream-if-stream-outcnt-has-been-change-by-sinit-in-sendmsg.patch
queue-4.14/pppoe-take-needed_headroom-of-lower-device-into-account-on-xmit.patch
queue-4.14/sctp-return-error-if-the-asoc-has-been-peeled-off-in-sctp_wait_for_sndbuf.patch
queue-4.14/netlink-reset-extack-earlier-in-netlink_rcv_skb.patch