ipv6: sr: fix out-of-bounds access in SRH validation

This patch fixes an out-of-bounds access in seg6_validate_srh() when the
trailing data is less than sizeof(struct sr6_tlv).

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c
index a855eb325b03..5f44ffed2576 100644
--- a/net/ipv6/seg6.c
+++ b/net/ipv6/seg6.c
@@ -53,6 +53,9 @@ bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len)
                 struct sr6_tlv *tlv;
                 unsigned int tlv_len;
 
+                if (trailing < sizeof(*tlv))
+                        return false;
+
                 tlv = (struct sr6_tlv *)((unsigned char *)srh + tlv_offset);
                 tlv_len = sizeof(*tlv) + tlv->len;