From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chuck Lever Subject: [PATCH] NET: Fix skb_truesize_check() assertion Date: Thu, 08 Nov 2007 11:59:19 -0500 Message-ID: <20071108165919.14014.56630.stgit@manray.1015granger.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from flpi185.sbcis.sbc.com ([207.115.20.187]:4249 "EHLO flpi185.prodigy.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759333AbXKHQ72 (ORCPT ); Thu, 8 Nov 2007 11:59:28 -0500 Received: from manray.1015granger.net (adsl-76-241-169-38.dsl.sfldmi.sbcglobal.net [76.241.169.38]) by flpi185.prodigy.net (8.13.8 out.dk.spool/8.13.8) with ESMTP id lA8GxRPi010032 for ; Thu, 8 Nov 2007 08:59:27 -0800 Received: from manray.1015granger.net (manray.1015granger.net [127.0.0.1]) by manray.1015granger.net (8.14.1/8.14.1) with ESMTP id lA8GxJXA014030 for ; Thu, 8 Nov 2007 11:59:19 -0500 Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org The intent of the assertion in skb_truesize_check() is to check for skb->truesize being decremented too much by other code, resulting in a wraparound below zero. The type of the right side of the comparison causes the compiler to promote the left side to an unsigned type, despite the presence of an explicit type cast. This defeats the check for negativity. Ensure both sides of the comparison are a signed type to prevent the implicit type conversion. Signed-off-by: Chuck Lever --- include/linux/skbuff.h | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 94e4991..91140fe 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -387,7 +387,9 @@ extern void skb_truesize_bug(struct sk_buff *skb); static inline void skb_truesize_check(struct sk_buff *skb) { - if (unlikely((int)skb->truesize < sizeof(struct sk_buff) + skb->len)) + int len = sizeof(struct sk_buff) + skb->len; + + if (unlikely((int)skb->truesize < len)) skb_truesize_bug(skb); }