Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932944Ab3D2Vmm (ORCPT ); Mon, 29 Apr 2013 17:42:42 -0400 Received: from mail-qe0-f44.google.com ([209.85.128.44]:62517 "EHLO mail-qe0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932908Ab3D2Vmh (ORCPT ); Mon, 29 Apr 2013 17:42:37 -0400 From: Benjamin Poirier To: "David S. Miller" , Eric Dumazet , Pavel Emelyanov , Cong Wang Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/3] unix/dgram: peek beyond 0-sized skbs Date: Mon, 29 Apr 2013 17:42:12 -0400 Message-Id: <1367271734-14379-1-git-send-email-bpoirier@suse.de> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1552 Lines: 45 "77c1090 net: fix infinite loop in __skb_recv_datagram()" (v3.8) introduced a regression: After that commit, recv can no longer peek beyond a 0-sized skb in the queue. __skb_recv_datagram() instead stops at the first skb with len == 0 and results in the system call failing with -EFAULT via skb_copy_datagram_iovec(). When peeking at an offset with 0-sized skb(s), each one of those is received only once, in sequence. The offset starts moving forward again after receiving datagrams with len > 0. Signed-off-by: Benjamin Poirier --- * v1 fix the case when SO_PEEK_OFF is used to set sk_peek_off beyond a 0-sized skb * v2 also fix the situation when sk_peek_off must advance to and beyond a 0-sized skb net/core/datagram.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/datagram.c b/net/core/datagram.c index 368f9c3..99c4f52 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -187,7 +187,8 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, skb_queue_walk(queue, skb) { *peeked = skb->peeked; if (flags & MSG_PEEK) { - if (*off >= skb->len && skb->len) { + if (*off >= skb->len && (skb->len || *off || + skb->peeked)) { *off -= skb->len; continue; } -- 1.7.10.4 -- 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/