From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755874Ab1G0Vt5 (ORCPT ); Wed, 27 Jul 2011 17:49:57 -0400 Received: from mga11.intel.com ([192.55.52.93]:36412 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755776Ab1G0Vte (ORCPT ); Wed, 27 Jul 2011 17:49:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,279,1309762800"; d="scan'208";a="35258487" From: Andi Kleen References: <20110727247.325703029@firstfloor.org> In-Reply-To: <20110727247.325703029@firstfloor.org> To: xufeng.zhang@windriver.com, paul.gortmaker@windriver.com, davem@davemloft.net, gregkh@suse.de, ak@linux.intel.com, linux-kernel@vger.kernel.org, stable@kernel.org, tim.bird@am.sony.com Subject: [PATCH] [94/99] udp/recvmsg: Clear MSG_TRUNC flag when starting over for a new packet Message-Id: <20110727214934.01BDE2403FF@tassilo.jf.intel.com> Date: Wed, 27 Jul 2011 14:49:34 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.35-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Xufeng Zhang [ Upstream commit 9cfaa8def1c795a512bc04f2aec333b03724ca2e ] Consider this scenario: When the size of the first received udp packet is bigger than the receive buffer, MSG_TRUNC bit is set in msg->msg_flags. However, if checksum error happens and this is a blocking socket, it will goto try_again loop to receive the next packet. But if the size of the next udp packet is smaller than receive buffer, MSG_TRUNC flag should not be set, but because MSG_TRUNC bit is not cleared in msg->msg_flags before receive the next packet, MSG_TRUNC is still set, which is wrong. Fix this problem by clearing MSG_TRUNC flag when starting over for a new packet. Signed-off-by: Xufeng Zhang Signed-off-by: Paul Gortmaker Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andi Kleen --- net/ipv4/udp.c | 3 +++ net/ipv6/udp.c | 3 +++ 2 files changed, 6 insertions(+) Index: linux-2.6.35.y/net/ipv4/udp.c =================================================================== --- linux-2.6.35.y.orig/net/ipv4/udp.c +++ linux-2.6.35.y/net/ipv4/udp.c @@ -1206,6 +1206,9 @@ csum_copy_err: if (noblock) return -EAGAIN; + + /* starting over for a new packet */ + msg->msg_flags &= ~MSG_TRUNC; goto try_again; } Index: linux-2.6.35.y/net/ipv6/udp.c =================================================================== --- linux-2.6.35.y.orig/net/ipv6/udp.c +++ linux-2.6.35.y/net/ipv6/udp.c @@ -447,6 +447,9 @@ csum_copy_err: if (noblock) return -EAGAIN; + + /* starting over for a new packet */ + msg->msg_flags &= ~MSG_TRUNC; goto try_again; }