From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753412Ab1GIFyu (ORCPT ); Sat, 9 Jul 2011 01:54:50 -0400 Received: from out5.smtp.messagingengine.com ([66.111.4.29]:37305 "EHLO out5.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752225Ab1GIFyg (ORCPT ); Sat, 9 Jul 2011 01:54:36 -0400 X-Sasl-enc: 6sWpOWdHCnKRQDSkgode4QnZVR1sV2I6dKtdlHHNrFiW 1310190875 X-Mailbox-Line: From gregkh@clark.kroah.org Fri Jul 8 15:51:22 2011 Message-Id: <20110708225122.081079051@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Fri, 08 Jul 2011 15:50:23 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Xufeng Zhang , Paul Gortmaker , "David S. Miller" Subject: [34/35] udp/recvmsg: Clear MSG_TRUNC flag when starting over for a new packet In-Reply-To: <20110708225343.GA14402@kroah.com> 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 us 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 --- net/ipv4/udp.c | 3 +++ net/ipv6/udp.c | 3 +++ 2 files changed, 6 insertions(+) --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1011,6 +1011,9 @@ csum_copy_err: if (noblock) return -EAGAIN; + + /* starting over for a new packet */ + msg->msg_flags &= ~MSG_TRUNC; goto try_again; } --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -306,6 +306,9 @@ csum_copy_err: if (noblock) return -EAGAIN; + + /* starting over for a new packet */ + msg->msg_flags &= ~MSG_TRUNC; goto try_again; }