4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: yujuan.qi <yujuan.qi@xxxxxxxxxxxx> commit 40413955ee265a5e42f710940ec78f5450d49149 upstream. in for(),if((optlen > 0) && (optptr[1] == 0)), enter infinite loop. Test: receive a packet which the ip length > 20 and the first byte of ip option is 0, produce this issue Signed-off-by: yujuan.qi <yujuan.qi@xxxxxxxxxxxx> Acked-by: Paul Moore <paul@xxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv4/cipso_ipv4.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/net/ipv4/cipso_ipv4.c +++ b/net/ipv4/cipso_ipv4.c @@ -1523,9 +1523,17 @@ unsigned char *cipso_v4_optptr(const str int taglen; for (optlen = iph->ihl*4 - sizeof(struct iphdr); optlen > 0; ) { - if (optptr[0] == IPOPT_CIPSO) + switch (optptr[0]) { + case IPOPT_CIPSO: return optptr; - taglen = optptr[1]; + case IPOPT_END: + return NULL; + case IPOPT_NOOP: + taglen = 1; + break; + default: + taglen = optptr[1]; + } optlen -= taglen; optptr += taglen; }