[Dnsmasq-discuss] dnsmasq doesn't reply the last option of dhcpv6 relay-forward packet after applying the patch of CVE-2017-14494

[yiwenchen]

Hi,


I found that dnsmasq doesn't reply dhcpv6 relay-forward packets after applying the patch of CVE-2017-14494.
It seems like the boundary check in the patch is wrong.

The following commit should fix the problem.
Could you please help confirm the issue?
Thank you very much.


---
src/rfc3315.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/rfc3315.c b/src/rfc3315.c
index c3c1c95..99b310a 100644
--- a/src/rfc3315.c
+++ b/src/rfc3315.c
@@ -216,7 +216,7 @@ static int dhcp6_maybe_relay(struct state *state, void *inbuff, size_t sz,

for (opt = opts; opt; opt = opt6_next(opt, end))
{
- if (opt6_ptr(opt, 0) + opt6_len(opt) >= end) {
+ if (opt6_ptr(opt, 0) + opt6_len(opt) > end) {
return 0;
}
int o = new_opt6(opt6_type(opt));
--
1.9.1

Best Regards,
Yiwen

[Simon Kelley]

You're right. Apologies for letting that slip through.

Patch applied.

Cheers,

Simon.

Hi,
 
I found that dnsmasq doesn't reply dhcpv6 relay-forward packets after
applying the patch of CVE-2017-14494.
It seems like the boundary check in the patch is wrong.
 
The following commit should fix the problem.
Could you please help confirm the issue?
Thank you very much.
 
 
---
 src/rfc3315.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 
diff --git a/src/rfc3315.c b/src/rfc3315.c
index c3c1c95..99b310a 100644
--- a/src/rfc3315.c
+++ b/src/rfc3315.c
@@ -216,7 +216,7 @@ static int dhcp6_maybe_relay(struct state *state,
void *inbuff, size_t sz,
 
   for (opt = opts; opt; opt = opt6_next(opt, end))
     {
- if (opt6_ptr(opt, 0) + opt6_len(opt) >= end) {
+ if (opt6_ptr(opt, 0) + opt6_len(opt) > end) {
         return 0;
       }
       int o = new_opt6(opt6_type(opt));
--
1.9.1
 
Best Regards,
Yiwen
 
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