ipvs: check that ip_vs_conn_tab_bits is between 8 and 20

ip_vs_conn_tab_bits may be provided by the user through the
conn_tab_bits module parameter. If this value is greater than 31, or
less than 0, the shift operator used to derive tab_size causes undefined
behaviour.

Fix this checking ip_vs_conn_tab_bits value to be in the range specified
in ipvs Kconfig. If not, simply use default value.

Fixes: 6f7edb4881bf ("IPVS: Allow boot time change of hash size")
Reported-by: Yi Chen <yiche@redhat.com>
Signed-off-by: Andrea Claudi <aclaudi@redhat.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index c100c6b..2c467c4 100644 (file)
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -1468,6 +1468,10 @@ int __init ip_vs_conn_init(void)
        int idx;
 
        /* Compute size and mask */
+       if (ip_vs_conn_tab_bits < 8 || ip_vs_conn_tab_bits > 20) {
+               pr_info("conn_tab_bits not in [8, 20]. Using default value\n");
+               ip_vs_conn_tab_bits = CONFIG_IP_VS_TAB_BITS;
+       }
        ip_vs_conn_tab_size = 1 << ip_vs_conn_tab_bits;
        ip_vs_conn_tab_mask = ip_vs_conn_tab_size - 1;