diff mbox series

[net-next,3/9] netfilter: bridge: check len before accessing more nh data

Message ID 20230308193033.13965-4-fw@strlen.de (mailing list archive)
State Accepted
Commit a7f1a2f43e683c8ffca691d45f2cb32c052158fa
Delegated to: Netdev Maintainers
Headers show
Series [net-next,1/9] netfilter: bridge: introduce broute meta statement | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 20 this patch: 20
netdev/cc_maintainers warning 5 maintainers not CCed: bridge@lists.linux-foundation.org pablo@netfilter.org kadlec@netfilter.org roopa@nvidia.com coreteam@netfilter.org
netdev/build_clang success Errors and warnings before: 18 this patch: 18
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 20 this patch: 20
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 74 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Florian Westphal March 8, 2023, 7:30 p.m. UTC 
From: Xin Long <lucien.xin@gmail.com>

In the while loop of br_nf_check_hbh_len(), similar to ip6_parse_tlv(),
before accessing 'nh[off + 1]', it should add a check 'len < 2'; and
before parsing IPV6_TLV_JUMBO, it should add a check 'optlen > len',
in case of overflows.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/bridge/br_netfilter_ipv6.c | 45 +++++++++++++++-------------------
 1 file changed, 20 insertions(+), 25 deletions(-)
diff mbox series

Patch

diff --git a/net/bridge/br_netfilter_ipv6.c b/net/bridge/br_netfilter_ipv6.c
index afd1c718b683..8be3c5c8b925 100644
--- a/net/bridge/br_netfilter_ipv6.c
+++ b/net/bridge/br_netfilter_ipv6.c
@@ -50,54 +50,49 @@  static int br_nf_check_hbh_len(struct sk_buff *skb)
 	u32 pkt_len;
 
 	if (!pskb_may_pull(skb, off + 8))
-		goto bad;
+		return -1;
 	nh = (unsigned char *)(ipv6_hdr(skb) + 1);
 	len = (nh[1] + 1) << 3;
 
 	if (!pskb_may_pull(skb, off + len))
-		goto bad;
+		return -1;
 	nh = skb_network_header(skb);
 
 	off += 2;
 	len -= 2;
-
 	while (len > 0) {
-		int optlen = nh[off + 1] + 2;
-
-		switch (nh[off]) {
-		case IPV6_TLV_PAD1:
-			optlen = 1;
-			break;
+		int optlen;
 
-		case IPV6_TLV_PADN:
-			break;
+		if (nh[off] == IPV6_TLV_PAD1) {
+			off++;
+			len--;
+			continue;
+		}
+		if (len < 2)
+			return -1;
+		optlen = nh[off + 1] + 2;
+		if (optlen > len)
+			return -1;
 
-		case IPV6_TLV_JUMBO:
+		if (nh[off] == IPV6_TLV_JUMBO) {
 			if (nh[off + 1] != 4 || (off & 3) != 2)
-				goto bad;
+				return -1;
 			pkt_len = ntohl(*(__be32 *)(nh + off + 2));
 			if (pkt_len <= IPV6_MAXPLEN ||
 			    ipv6_hdr(skb)->payload_len)
-				goto bad;
+				return -1;
 			if (pkt_len > skb->len - sizeof(struct ipv6hdr))
-				goto bad;
+				return -1;
 			if (pskb_trim_rcsum(skb,
 					    pkt_len + sizeof(struct ipv6hdr)))
-				goto bad;
+				return -1;
 			nh = skb_network_header(skb);
-			break;
-		default:
-			if (optlen > len)
-				goto bad;
-			break;
 		}
 		off += optlen;
 		len -= optlen;
 	}
-	if (len == 0)
-		return 0;
-bad:
-	return -1;
+
+	return len ? -1 : 0;
 }
 
 int br_validate_ipv6(struct net *net, struct sk_buff *skb)