kernel/0001-ipv6-avoid-overflow-of-offset-in-ip6_find_1stfragopt.patch
Justin M. Forbes 79d288fe2c Linux v4.12.3
2017-07-21 09:24:12 -05:00

55 lines
1.7 KiB
Diff

From 6399f1fae4ec29fab5ec76070435555e256ca3a6 Mon Sep 17 00:00:00 2001
From: Sabrina Dubroca <sd@queasysnail.net>
Date: Wed, 19 Jul 2017 22:28:55 +0200
Subject: [PATCH] ipv6: avoid overflow of offset in ip6_find_1stfragopt
In some cases, offset can overflow and can cause an infinite loop in
ip6_find_1stfragopt(). Make it unsigned int to prevent the overflow, and
cap it at IPV6_MAXPLEN, since packets larger than that should be invalid.
This problem has been here since before the beginning of git history.
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv6/output_core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index e9065b8..abb2c30 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -78,7 +78,7 @@ EXPORT_SYMBOL(ipv6_select_ident);
int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
{
- u16 offset = sizeof(struct ipv6hdr);
+ unsigned int offset = sizeof(struct ipv6hdr);
unsigned int packet_len = skb_tail_pointer(skb) -
skb_network_header(skb);
int found_rhdr = 0;
@@ -86,6 +86,7 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
while (offset <= packet_len) {
struct ipv6_opt_hdr *exthdr;
+ unsigned int len;
switch (**nexthdr) {
@@ -111,7 +112,10 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
offset);
- offset += ipv6_optlen(exthdr);
+ len = ipv6_optlen(exthdr);
+ if (len + offset >= IPV6_MAXPLEN)
+ return -EINVAL;
+ offset += len;
*nexthdr = &exthdr->nexthdr;
}
--
2.9.4