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authorEric Dumazet <edumazet@google.com>2017-01-23 16:43:06 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-18 16:39:26 +0100
commit41e07a7e01d951cfd4c9a7dac90c921269d89513 (patch)
tree0d667aa8ab4d111148b5a5bb7eaca873e82bdc75 /net/ipv6
parente6c654c9c09258dc0f82d1baa9ce69aa68bc735e (diff)
ipv6: fix ip6_tnl_parse_tlv_enc_lim()
[ Upstream commit fbfa743a9d2a0ffa24251764f10afc13eb21e739 ] This function suffers from multiple issues. First one is that pskb_may_pull() may reallocate skb->head, so the 'raw' pointer needs either to be reloaded or not used at all. Second issue is that NEXTHDR_DEST handling does not validate that the options are present in skb->data, so we might read garbage or access non existent memory. With help from Willem de Bruijn. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/ip6_tunnel.c34
1 files changed, 22 insertions, 12 deletions
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 2994d1f1a661..3fed666b95ae 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -479,18 +479,19 @@ ip6_tnl_dev_uninit(struct net_device *dev)
__u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw)
{
- const struct ipv6hdr *ipv6h = (const struct ipv6hdr *) raw;
- __u8 nexthdr = ipv6h->nexthdr;
- __u16 off = sizeof(*ipv6h);
+ const struct ipv6hdr *ipv6h = (const struct ipv6hdr *)raw;
+ unsigned int nhoff = raw - skb->data;
+ unsigned int off = nhoff + sizeof(*ipv6h);
+ u8 next, nexthdr = ipv6h->nexthdr;
while (ipv6_ext_hdr(nexthdr) && nexthdr != NEXTHDR_NONE) {
- __u16 optlen = 0;
struct ipv6_opt_hdr *hdr;
- if (raw + off + sizeof(*hdr) > skb->data &&
- !pskb_may_pull(skb, raw - skb->data + off + sizeof (*hdr)))
+ u16 optlen;
+
+ if (!pskb_may_pull(skb, off + sizeof(*hdr)))
break;
- hdr = (struct ipv6_opt_hdr *) (raw + off);
+ hdr = (struct ipv6_opt_hdr *)(skb->data + off);
if (nexthdr == NEXTHDR_FRAGMENT) {
struct frag_hdr *frag_hdr = (struct frag_hdr *) hdr;
if (frag_hdr->frag_off)
@@ -501,20 +502,29 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw)
} else {
optlen = ipv6_optlen(hdr);
}
+ /* cache hdr->nexthdr, since pskb_may_pull() might
+ * invalidate hdr
+ */
+ next = hdr->nexthdr;
if (nexthdr == NEXTHDR_DEST) {
- __u16 i = off + 2;
+ u16 i = 2;
+
+ /* Remember : hdr is no longer valid at this point. */
+ if (!pskb_may_pull(skb, off + optlen))
+ break;
+
while (1) {
struct ipv6_tlv_tnl_enc_lim *tel;
/* No more room for encapsulation limit */
- if (i + sizeof (*tel) > off + optlen)
+ if (i + sizeof(*tel) > optlen)
break;
- tel = (struct ipv6_tlv_tnl_enc_lim *) &raw[i];
+ tel = (struct ipv6_tlv_tnl_enc_lim *) skb->data + off + i;
/* return index of option if found and valid */
if (tel->type == IPV6_TLV_TNL_ENCAP_LIMIT &&
tel->length == 1)
- return i;
+ return i + off - nhoff;
/* else jump to next option */
if (tel->type)
i += tel->length + 2;
@@ -522,7 +532,7 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw)
i++;
}
}
- nexthdr = hdr->nexthdr;
+ nexthdr = next;
off += optlen;
}
return 0;