| From | Andi Kleen <> | Subject | [PATCH] [124/223] netfilter: NF_HOOK_COND has wrong conditional | Date | Mon, 13 Dec 2010 00:47:05 +0100 (CET) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Eric Paris <eparis@redhat.com>
commit ac5aa2e3332ec04889074afdbd1479424d0227a5 upstream.
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 <eparis@redhat.com> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Andi Kleen <ak@linux.intel.com>
--- include/linux/netfilter.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux/include/linux/netfilter.h =================================================================== --- linux.orig/include/linux/netfilter.h +++ linux/include/linux/netfilter.h @@ -215,7 +215,7 @@ NF_HOOK_COND(uint8_t pf, unsigned int ho 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; }
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