[PATCH 4.11 023/115] ipv6: Check ip6_find_1stfragopt() return value properly.

Greg Kroah-Hartman
2017-06-05T16:50:11Z

From: "David S. Miller" <davem@davemloft.net>

[ Upstream commit 7dd7eb9513bd02184d45f000ab69d78cb1fa1531 ]

Do not use unsigned variables to see if it returns a negative
error or not.

Fixes: 2423496af35d ("ipv6: Prevent overrun when parsing v6 header options")
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/ip6_offload.c | 9 ++++-----
net/ipv6/ip6_output.c | 7 +++----
net/ipv6/udp_offload.c | 8 +++++---
3 files changed, 12 insertions(+), 12 deletions(-)

--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -63,7 +63,6 @@ static struct sk_buff *ipv6_gso_segment(
const struct net_offload *ops;
int proto;
struct frag_hdr *fptr;
- unsigned int unfrag_ip6hlen;
unsigned int payload_len;
u8 *prevhdr;
int offset = 0;
@@ -116,10 +115,10 @@ static struct sk_buff *ipv6_gso_segment(
skb->network_header = (u8 *)ipv6h - skb->head;

if (udpfrag) {
- unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
- if (unfrag_ip6hlen < 0)
- return ERR_PTR(unfrag_ip6hlen);
- fptr = (struct frag_hdr *)((u8 *)ipv6h + unfrag_ip6hlen);
+ int err = ip6_find_1stfragopt(skb, &prevhdr);
+ if (err < 0)
+ return ERR_PTR(err);
+ fptr = (struct frag_hdr *)((u8 *)ipv6h + err);
fptr->frag_off = htons(offset);
if (skb->next)
fptr->frag_off |= htons(IP6_MF);
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -597,11 +597,10 @@ int ip6_fragment(struct net *net, struct
int ptr, offset = 0, err = 0;
u8 *prevhdr, nexthdr = 0;

- hlen = ip6_find_1stfragopt(skb, &prevhdr);
- if (hlen < 0) {
- err = hlen;
+ err = ip6_find_1stfragopt(skb, &prevhdr);
+ if (err < 0)
goto fail;
- }
+ hlen = err;
nexthdr = *prevhdr;

mtu = ip6_skb_dst_mtu(skb);
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -29,6 +29,7 @@ static struct sk_buff *udp6_ufo_fragment
u8 frag_hdr_sz = sizeof(struct frag_hdr);
__wsum csum;
int tnl_hlen;
+ int err;

mss = skb_shinfo(skb)->gso_size;
if (unlikely(skb->len <= mss))
@@ -90,9 +91,10 @@ static struct sk_buff *udp6_ufo_fragment
/* Find the unfragmentable header and shift it left by frag_hdr_sz
* bytes to insert fragment header.
*/
- unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
- if (unfrag_ip6hlen < 0)
- return ERR_PTR(unfrag_ip6hlen);
+ err = ip6_find_1stfragopt(skb, &prevhdr);
+ if (err < 0)
+ return ERR_PTR(err);
+ unfrag_ip6hlen = err;
nexthdr = *prevhdr;
*prevhdr = NEXTHDR_FRAGMENT;
unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +