On 2017-04-02 20:26, Eric Dumazet wrote:
On Sun, 2017-04-02 at 10:14 -0700, Eric Dumazet wrote:
Could that be that netfilter does not abort earlier if TCP header is
completely wrong ?
Yes, I wonder if this patch would be better, unless we replicate the
th->doff sanity check in all netfilter modules dissecting TCP frames.
diff --git a/net/netfilter/xt_tcpudp.c b/net/netfilter/xt_tcpudp.c
index
ade024c90f4f129a7c384e9e1cbfdb8ffe73065f..8cb4eadd5ba1c20e74bc27ee52a0bc36a5b26725
100644
--- a/net/netfilter/xt_tcpudp.c
+++ b/net/netfilter/xt_tcpudp.c
@@ -103,11 +103,11 @@ static bool tcp_mt(const struct sk_buff *skb,
struct xt_action_param *par)
if (!NF_INVF(tcpinfo, XT_TCP_INV_FLAGS,
(((unsigned char *)th)[13] & tcpinfo->flg_mask) ==
tcpinfo->flg_cmp))
return false;
+ if (th->doff * 4 < sizeof(_tcph)) {
+ par->hotdrop = true;
+ return false;
+ }
if (tcpinfo->option) {
- if (th->doff * 4 < sizeof(_tcph)) {
- par->hotdrop = true;
- return false;
- }
if (!tcp_find_option(tcpinfo->option, skb, par->thoff,
th->doff*4 - sizeof(_tcph),
tcpinfo->invflags & XT_TCP_INV_OPTION,
I modified patch a little as:
if (th->doff * 4 < sizeof(_tcph)) {
par->hotdrop = true;
WARN_ON_ONCE(!tcpinfo->option);
return false;
}
And it did triggered WARN once at morning, and didn't hit KASAN. I will
run for a while more, to see if it is ok, and then if stable, will try
to enable SFQ again.
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