[PATCH 3.18 02/56] Cipso: cipso_v4_optptr enter infinite loop

From: Greg Kroah-Hartman
Date: Mon Sep 03 2018 - 12:50:49 EST


3.18-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
@@ -1591,9 +1591,17 @@ 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;
}