From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753051AbaELBmc (ORCPT ); Sun, 11 May 2014 21:42:32 -0400 Received: from 1wt.eu ([62.212.114.60]:34544 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752937AbaELBm1 (ORCPT ); Sun, 11 May 2014 21:42:27 -0400 Message-Id: <20140512003204.668886056@1wt.eu> User-Agent: quilt/0.48-1 Date: Mon, 12 May 2014 02:33:37 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Daniel Borkmann , Stephen Hemminger , Arnaldo Carvalho de Melo , "David S. Miller" , Willy Tarreau Subject: [ 097/143] net: llc: fix use after free in llc_ui_recvmsg In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann [ Upstream commit 4d231b76eef6c4a6bd9c96769e191517765942cb ] While commit 30a584d944fb fixes datagram interface in LLC, a use after free bug has been introduced for SOCK_STREAM sockets that do not make use of MSG_PEEK. The flow is as follow ... if (!(flags & MSG_PEEK)) { ... sk_eat_skb(sk, skb, false); ... } ... if (used + offset < skb->len) continue; ... where sk_eat_skb() calls __kfree_skb(). Therefore, cache original length and work on skb_len to check partial reads. Fixes: 30a584d944fb ("[LLX]: SOCK_DGRAM interface fixes") Signed-off-by: Daniel Borkmann Cc: Stephen Hemminger Cc: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller Signed-off-by: Willy Tarreau --- net/llc/af_llc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c index 606b6ad..f62b63e 100644 --- a/net/llc/af_llc.c +++ b/net/llc/af_llc.c @@ -669,7 +669,7 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock, struct llc_sock *llc = llc_sk(sk); size_t copied = 0; u32 peek_seq = 0; - u32 *seq; + u32 *seq, skb_len; unsigned long used; int target; /* Read at least this many bytes */ long timeo; @@ -767,6 +767,7 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock, } continue; found_ok_skb: + skb_len = skb->len; /* Ok so how much can we use? */ used = skb->len - offset; if (len < used) @@ -797,7 +798,7 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock, goto copy_uaddr; /* Partial read */ - if (used + offset < skb->len) + if (used + offset < skb_len) continue; } while (len > 0); -- 1.7.12.2.21.g234cd45.dirty