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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 1/4] netfilter: nf_flow_table: fix big-endian integer overflow
Date: Thu, 26 Dec 2019 17:39:53 +0100
Message-ID: <20191226163956.672174-2-pablo@netfilter.org> (raw)
In-Reply-To: <20191226163956.672174-1-pablo@netfilter.org>

From: Arnd Bergmann <arnd@arndb.de>

In some configurations, gcc reports an integer overflow:

net/netfilter/nf_flow_table_offload.c: In function 'nf_flow_rule_match':
net/netfilter/nf_flow_table_offload.c:80:21: error: unsigned conversion from 'int' to '__be16' {aka 'short unsigned int'} changes value from '327680' to '0' [-Werror=overflow]
   mask->tcp.flags = TCP_FLAG_RST | TCP_FLAG_FIN;
                     ^~~~~~~~~~~~

From what I can tell, we want the upper 16 bits of these constants,
so they need to be shifted in cpu-endian mode.

Fixes: c29f74e0df7a ("netfilter: nf_flow_table: hardware offload support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_flow_table_offload.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_flow_table_offload.c b/net/netfilter/nf_flow_table_offload.c
index de7a0d1e15c8..0d72e5ccb47b 100644
--- a/net/netfilter/nf_flow_table_offload.c
+++ b/net/netfilter/nf_flow_table_offload.c
@@ -88,7 +88,7 @@ static int nf_flow_rule_match(struct nf_flow_match *match,
 	switch (tuple->l4proto) {
 	case IPPROTO_TCP:
 		key->tcp.flags = 0;
-		mask->tcp.flags = TCP_FLAG_RST | TCP_FLAG_FIN;
+		mask->tcp.flags = cpu_to_be16(be32_to_cpu(TCP_FLAG_RST | TCP_FLAG_FIN) >> 16);
 		match->dissector.used_keys |= BIT(FLOW_DISSECTOR_KEY_TCP);
 		break;
 	case IPPROTO_UDP:
-- 
2.11.0


  reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-26 16:39 [PATCH 0/4] Netfilter fixes for net Pablo Neira Ayuso
2019-12-26 16:39 ` Pablo Neira Ayuso [this message]
2019-12-26 16:39 ` [PATCH 2/4] selftests: netfilter: extend flowtable test script with dnat rule Pablo Neira Ayuso
2019-12-26 16:39 ` [PATCH 3/4] netfilter: ebtables: compat: reject all padding in matches/watchers Pablo Neira Ayuso
2019-12-26 16:39 ` [PATCH 4/4] netfilter: nft_tproxy: Fix port selector on Big Endian Pablo Neira Ayuso
2019-12-26 21:11 ` [PATCH 0/4] Netfilter fixes for net David Miller

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