Patch "ipv6: accept 64k - 1 packet length in ip6_find_1stfragopt()" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

ipv6: accept 64k - 1 packet length in ip6_find_1stfragopt()

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     ipv6-accept-64k-1-packet-length-in-ip6_find_1stfragopt.patch

and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Stefano Brivio <[email protected]>
Date: Fri, 18 Aug 2017 14:40:53 +0200
Subject: ipv6: accept 64k - 1 packet length in ip6_find_1stfragopt()

From: Stefano Brivio <[email protected]>

[ 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.

---
 net/ipv6/output_core.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

@@ -86,7 +86,6 @@ int ip6_find_1stfragopt(struct sk_buff *
 
 	while (offset <= packet_len) {
 		struct ipv6_opt_hdr *exthdr;
-		unsigned int len;
 
 		switch (**nexthdr) {
 

@@ -112,10 +111,9 @@ int ip6_find_1stfragopt(struct sk_buff *
 
 		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;
 	}
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/ipv6-accept-64k-1-packet-length-in-ip6_find_1stfragopt.patch queue-4.12/sctp-avoid-out-of-bounds-reads-from-address-storage.patch queue-4.12/cxgb4-fix-stack-out-of-bounds-read-due-to-wrong-size-to-t4_record_mbox.patch