From mboxrd@z Thu Jan 1 00:00:00 1970 From: kaber@trash.net Subject: [PATCH 1/2] netfilter: NF_HOOK_COND has wrong conditional Date: Fri, 12 Nov 2010 16:19:31 +0100 Message-ID: <1289575172-7272-2-git-send-email-kaber@trash.net> References: <1289575172-7272-1-git-send-email-kaber@trash.net> Cc: netfilter-devel@vger.kernel.org, netdev@vger.kernel.org, Eric Paris , stable@kernel.org, Patrick McHardy To: davem@davemloft.net Return-path: Received: from stinky.trash.net ([213.144.137.162]:34575 "EHLO stinky.trash.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932100Ab0KLPWb (ORCPT ); Fri, 12 Nov 2010 10:22:31 -0500 In-Reply-To: <1289575172-7272-1-git-send-email-kaber@trash.net> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Paris The NF_HOOK_COND returns 0 when it shouldn't due to what I believe to be an error in the code as the order of operations is not what was intended. C will evalutate == before =. Which means ret is getting set to the bool result, rather than the return value of the function call. The code says if (ret = function() == 1) when it meant to say: if ((ret = function()) == 1) Normally the compiler would warn, but it doesn't notice it because its a actually complex conditional and so the wrong code is wrapped in an explict set of () [exactly what the compiler wants you to do if this was intentional]. Fixing this means that errors when netfilter denies a packet get propagated back up the stack rather than lost. Problem introduced by commit 2249065f (netfilter: get rid of the grossness in netfilter.h). Signed-off-by: Eric Paris Cc: stable@kernel.org Signed-off-by: Patrick McHardy --- include/linux/netfilter.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h index 89341c3..03317c8 100644 --- a/include/linux/netfilter.h +++ b/include/linux/netfilter.h @@ -215,7 +215,7 @@ NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb, int ret; if (!cond || - (ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN) == 1)) + ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1)) ret = okfn(skb); return ret; } -- 1.7.3.2