Messages in this thread Patch in this message | | | From | Eric Paris <> | Subject | [PATCH] netfilter: NF_HOOK_COND has wrong conditional | Date | Thu, 11 Nov 2010 14:09:54 -0500 |
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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.
Signed-off-by: Eric Paris <eparis@redhat.com> ---
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; }
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