netfilter: nf_flow_table: fix big-endian integer overflow

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: c29f74e0df ("netfilter: nf_flow_table: hardware offload support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Arnd Bergmann 2019-12-10 21:24:28 +01:00 committed by Pablo Neira Ayuso
parent 0fd260056e
commit c9b3b8207b

View File

@ -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: