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authorStefan Nuernberger <snu@amazon.com>2018-09-17 19:46:53 +0200
committerDavid S. Miller <davem@davemloft.net>2018-09-17 19:37:46 -0700
commit076ed3da0c9b2f88d9157dbe7044a45641ae369e (patch)
treef40d60c2bccd9cee2a8b592955b0c1b500c76b01 /net/ipv4/cipso_ipv4.c
parent0020f5c807ef67954d9210eea0ba17a6134cdf7d (diff)
net/ipv4: defensive cipso option parsing
commit 40413955ee26 ("Cipso: cipso_v4_optptr enter infinite loop") fixed a possible infinite loop in the IP option parsing of CIPSO. The fix assumes that ip_options_compile filtered out all zero length options and that no other one-byte options beside IPOPT_END and IPOPT_NOOP exist. While this assumption currently holds true, add explicit checks for zero length and invalid length options to be safe for the future. Even though ip_options_compile should have validated the options, the introduction of new one-byte options can still confuse this code without the additional checks. Signed-off-by: Stefan Nuernberger <snu@amazon.com> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Simon Veith <sveith@amazon.de> Cc: stable@vger.kernel.org Acked-by: Paul Moore <paul@paul-moore.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/cipso_ipv4.c')
-rw-r--r--net/ipv4/cipso_ipv4.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 82178cc69c96..777fa3b7fb13 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1512,7 +1512,7 @@ static int cipso_v4_parsetag_loc(const struct cipso_v4_doi *doi_def,
*
* Description:
* Parse the packet's IP header looking for a CIPSO option. Returns a pointer
- * to the start of the CIPSO option on success, NULL if one if not found.
+ * to the start of the CIPSO option on success, NULL if one is not found.
*
*/
unsigned char *cipso_v4_optptr(const struct sk_buff *skb)
@@ -1522,10 +1522,8 @@ unsigned char *cipso_v4_optptr(const struct sk_buff *skb)
int optlen;
int taglen;
- for (optlen = iph->ihl*4 - sizeof(struct iphdr); optlen > 0; ) {
+ for (optlen = iph->ihl*4 - sizeof(struct iphdr); optlen > 1; ) {
switch (optptr[0]) {
- case IPOPT_CIPSO:
- return optptr;
case IPOPT_END:
return NULL;
case IPOPT_NOOP:
@@ -1534,6 +1532,11 @@ unsigned char *cipso_v4_optptr(const struct sk_buff *skb)
default:
taglen = optptr[1];
}
+ if (!taglen || taglen > optlen)
+ return NULL;
+ if (optptr[0] == IPOPT_CIPSO)
+ return optptr;
+
optlen -= taglen;
optptr += taglen;
}