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

BugLink: http://bugs.launchpad.net/bugs/1688499
[ Upstream commit 2f3bb64247b5b083d05ccecad9c2e139bbfdc294 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c
index a855eb325b030a666fe92c56a2d432c77d9dfe7a..5f44ffed25768d83c31b31295474c5ecf623e986 100644 (file)
--- 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;