4.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
[ Upstream commit 6399f1fae4ec29fab5ec76070435555e256ca3a6 ]
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@xxxxxxxxxxxxxxx>
Acked-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv6/output_core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- 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 *
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 *
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;
}