Patch "net: avoid signed overflows for SO_{SND|RCV}BUFFORCE" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    net: avoid signed overflows for SO_{SND|RCV}BUFFORCE

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:
     net-avoid-signed-overflows-for-so_-snd-rcv-bufforce.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 Thu Dec  8 07:18:57 CET 2016
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 2 Dec 2016 09:44:53 -0800
Subject: net: avoid signed overflows for SO_{SND|RCV}BUFFORCE

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit b98b0bc8c431e3ceb4b26b0dfc8db509518fb290 ]

CAP_NET_ADMIN users should not be allowed to set negative
sk_sndbuf or sk_rcvbuf values, as it can lead to various memory
corruptions, crashes, OOM...

Note that before commit 82981930125a ("net: cleanups in
sock_setsockopt()"), the bug was even more serious, since SO_SNDBUF
and SO_RCVBUF were vulnerable.

This needs to be backported to all known linux kernels.

Again, many thanks to syzkaller team for discovering this gem.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/sock.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -745,7 +745,7 @@ int sock_setsockopt(struct socket *sock,
 		val = min_t(u32, val, sysctl_wmem_max);
 set_sndbuf:
 		sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
-		sk->sk_sndbuf = max_t(u32, val * 2, SOCK_MIN_SNDBUF);
+		sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);
 		/* Wake up sending tasks if we upped the value. */
 		sk->sk_write_space(sk);
 		break;
@@ -781,7 +781,7 @@ set_rcvbuf:
 		 * returning the value we actually used in getsockopt
 		 * is the most desirable behavior.
 		 */
-		sk->sk_rcvbuf = max_t(u32, val * 2, SOCK_MIN_RCVBUF);
+		sk->sk_rcvbuf = max_t(int, val * 2, SOCK_MIN_RCVBUF);
 		break;
 
 	case SO_RCVBUFFORCE:


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

queue-4.4/virtio-net-add-a-missing-synchronize_net.patch
queue-4.4/net-dccp-fix-use-after-free-in-dccp_invalid_packet.patch
queue-4.4/net-avoid-signed-overflows-for-so_-snd-rcv-bufforce.patch
queue-4.4/packet-fix-race-condition-in-packet_set_ring.patch