Patch "ipv4: provide stronger user input validation in nl_fib_input()" has been added to the 4.4-stable tree

Patch "ipv4: provide stronger user input validation in nl_fib_input()" has been added to the 4.4-stable tree

[gregkh]

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

    ipv4: provide stronger user input validation in nl_fib_input()

to the 4.4-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:
     ipv4-provide-stronger-user-input-validation-in-nl_fib_input.patch
and it can be found in the queue-4.4 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 Mon Mar 27 18:22:09 CEST 2017
From: Eric Dumazet <edumazet@google.com>
Date: Tue, 21 Mar 2017 19:22:28 -0700
Subject: ipv4: provide stronger user input validation in nl_fib_input()

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit c64c0b3cac4c5b8cb093727d2c19743ea3965c0b ]

Alexander reported a KMSAN splat caused by reads of uninitialized
field (tb_id_in) from user provided struct fib_result_nl

It turns out nl_fib_input() sanity tests on user input is a bit
wrong :

User can pretend nlh->nlmsg_len is big enough, but provide
at sendmsg() time a too small buffer.

Reported-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/fib_frontend.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1080,7 +1080,8 @@ static void nl_fib_input(struct sk_buff
 
 	net = sock_net(skb->sk);
 	nlh = nlmsg_hdr(skb);
-	if (skb->len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len ||
+	if (skb->len < nlmsg_total_size(sizeof(*frn)) ||
+	    skb->len < nlh->nlmsg_len ||
 	    nlmsg_len(nlh) < sizeof(*frn))
 		return;
 


Patches currently in stable-queue which might be from edumazet@google.com are

queue-4.4/ipv4-provide-stronger-user-input-validation-in-nl_fib_input.patch
queue-4.4/tcp-initialize-icsk_ack.lrcvtime-at-session-start-time.patch
queue-4.4/net-properly-release-sk_frag.page.patch