Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754826AbaANAnr (ORCPT ); Mon, 13 Jan 2014 19:43:47 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:54360 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753821AbaANA23 (ORCPT ); Mon, 13 Jan 2014 19:28:29 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , Stephen Hemminger , Arnaldo Carvalho de Melo , "David S. Miller" Subject: [PATCH 3.12 37/77] net: llc: fix use after free in llc_ui_recvmsg Date: Mon, 13 Jan 2014 16:27:58 -0800 Message-Id: <20140114002753.555282448@linuxfoundation.org> X-Mailer: git-send-email 1.8.5.1.163.gd7aced9 In-Reply-To: <20140114002752.497010554@linuxfoundation.org> References: <20140114002752.497010554@linuxfoundation.org> User-Agent: quilt/0.61-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.12-stable 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: Greg Kroah-Hartman --- net/llc/af_llc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/net/llc/af_llc.c +++ b/net/llc/af_llc.c @@ -715,7 +715,7 @@ static int llc_ui_recvmsg(struct kiocb * unsigned long cpu_flags; 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; @@ -812,6 +812,7 @@ static int llc_ui_recvmsg(struct kiocb * } continue; found_ok_skb: + skb_len = skb->len; /* Ok so how much can we use? */ used = skb->len - offset; if (len < used) @@ -844,7 +845,7 @@ static int llc_ui_recvmsg(struct kiocb * } /* Partial read */ - if (used + offset < skb->len) + if (used + offset < skb_len) continue; } while (len > 0); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/