From: Stefano Brivio <sbrivio@xxxxxxxxxx>
This patch has been added to the v4.1 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit 3de33e1ba0506723ab25734e098cf280ecc34756 ]
A packet length of exactly IPV6_MAXPLEN is allowed, we should
refuse parsing options only if the size is 64KiB or more.
While at it, remove one extra variable and one assignment which
were also introduced by the commit that introduced the size
check. Checking the sum 'offset + len' and only later adding
'len' to 'offset' doesn't provide any advantage over directly
summing to 'offset' and checking it.
Fixes: 6399f1fae4ec ("ipv6: avoid overflow of offset in ip6_find_1stfragopt")
Signed-off-by: Stefano Brivio <sbrivio@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
---
net/ipv6/output_core.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index 292ef2e584db..7c6159b1481a 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -84,7 +84,6 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
while (offset <= packet_len) {
struct ipv6_opt_hdr *exthdr;
- unsigned int len;
switch (**nexthdr) {
@@ -110,10 +109,9 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
offset);
- len = ipv6_optlen(exthdr);
- if (len + offset >= IPV6_MAXPLEN)
+ offset += ipv6_optlen(exthdr);
+ if (offset > IPV6_MAXPLEN)
return -EINVAL;
- offset += len;
*nexthdr = &exthdr->nexthdr;
}
--
2.11.0