From: Rohit Thapliyal <[email protected]>
np checked for NULL and then dereferenced. It should be modified
for NULL case.
Signed-off-by: Rohit Thapliyal <[email protected]>
Signed-off-by: Manjeet Pawar <[email protected]>
---
net/ipv6/ip6_output.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 1dfc402..c2afa14 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -205,14 +205,15 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
/*
* Fill in the IPv6 header
*/
- if (np)
+ if (np) {
hlimit = np->hop_limit;
+ ip6_flow_hdr(
+ hdr, tclass, ip6_make_flowlabel(
+ net, skb, fl6->flowlabel,
+ np->autoflowlabel, fl6));
+ }
if (hlimit < 0)
hlimit = ip6_dst_hoplimit(dst);
- ip6_flow_hdr(hdr, tclass, ip6_make_flowlabel(net, skb, fl6->flowlabel,
- np->autoflowlabel, fl6));
-
hdr->payload_len = htons(seg_len);
hdr->nexthdr = proto;
hdr->hop_limit = hlimit;
--
1.9.1
On 22.11.2016 07:27, Manjeet Pawar wrote:
> From: Rohit Thapliyal <[email protected]>
>
> np checked for NULL and then dereferenced. It should be modified
> for NULL case.
>
> Signed-off-by: Rohit Thapliyal <[email protected]>
> Signed-off-by: Manjeet Pawar <[email protected]>
> ---
> net/ipv6/ip6_output.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index 1dfc402..c2afa14 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -205,14 +205,15 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
> /*
> * Fill in the IPv6 header
> */
> - if (np)
> + if (np) {
> hlimit = np->hop_limit;
> + ip6_flow_hdr(
> + hdr, tclass, ip6_make_flowlabel(
> + net, skb, fl6->flowlabel,
> + np->autoflowlabel, fl6));
> + }
> if (hlimit < 0)
> hlimit = ip6_dst_hoplimit(dst);
>
> - ip6_flow_hdr(hdr, tclass, ip6_make_flowlabel(net, skb, fl6->flowlabel,
> - np->autoflowlabel, fl6));
> -
> hdr->payload_len = htons(seg_len);
> hdr->nexthdr = proto;
> hdr->hop_limit = hlimit;
>
We always should initialize hdr and not skip the ip6_flow_hdr call.
Do you saw a bug or did you find this by code review? I wonder if np can
actually be NULL at this point. Maybe we can just eliminate the NULL check.
Thanks,
Hannes
From: Hannes Frederic Sowa <[email protected]>
Date: Tue, 22 Nov 2016 13:26:45 +0100
> On 22.11.2016 07:27, Manjeet Pawar wrote:
>> From: Rohit Thapliyal <[email protected]>
>>
>> np checked for NULL and then dereferenced. It should be modified
>> for NULL case.
>>
>> Signed-off-by: Rohit Thapliyal <[email protected]>
>> Signed-off-by: Manjeet Pawar <[email protected]>
>> ---
>> net/ipv6/ip6_output.c | 9 +++++----
>> 1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
>> index 1dfc402..c2afa14 100644
>> --- a/net/ipv6/ip6_output.c
>> +++ b/net/ipv6/ip6_output.c
>> @@ -205,14 +205,15 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
>> /*
>> * Fill in the IPv6 header
>> */
>> - if (np)
>> + if (np) {
>> hlimit = np->hop_limit;
>> + ip6_flow_hdr(
>> + hdr, tclass, ip6_make_flowlabel(
>> + net, skb, fl6->flowlabel,
>> + np->autoflowlabel, fl6));
>> + }
>> if (hlimit < 0)
>> hlimit = ip6_dst_hoplimit(dst);
>>
>> - ip6_flow_hdr(hdr, tclass, ip6_make_flowlabel(net, skb, fl6->flowlabel,
>> - np->autoflowlabel, fl6));
>> -
>> hdr->payload_len = htons(seg_len);
>> hdr->nexthdr = proto;
>> hdr->hop_limit = hlimit;
>>
>
>
> We always should initialize hdr and not skip the ip6_flow_hdr call.
>
> Do you saw a bug or did you find this by code review? I wonder if np can
> actually be NULL at this point. Maybe we can just eliminate the NULL check.
Also the indentation is really off.
On 23.11.2016 05:45, Rohit Thapliyal wrote:
> |>On 22.11.2016 07:27, Manjeet Pawar wrote:
> >> From: Rohit Thapliyal <[email protected] <mailto:[email protected]>>
> >>
> >> np checked for NULL and then dereferenced. It should be modified
> >> for NULL case.
> >>
> >> Signed-off-by: Rohit Thapliyal <[email protected]
> <mailto:[email protected]>>>
> >> Signed-off-by: Manjeet Pawar <[email protected]
> <mailto:[email protected]>>>
> >> ---
> >> net/ipv6/ip6_output.c | 9 +++++----
> >> 1 file changed, 5 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> >> index 1dfc402..c2afa14 100644
> >> --- a/net/ipv6/ip6_output.c
> >> +++ b/net/ipv6/ip6_output.c
> >> @@ -205,14 +205,15 @@ int ip6_xmit(const struct sock *sk, struct sk_buff
> *skb, struct flowi6 *fl6,
> >> /*
> >> * Fill in the IPv6 header
> >> */
> >> - if (np)
> >> + if (np) {
> >> hlimit = np->hop_limit;
> >> + ip6_flow_hdr(
> >> + hdr, tclass, ip6_make_flowlabel(
> >> + net, skb, fl6->flowlabel,
> >> + np->autoflowlabel, fl6));
> >> + }
> >> if (hlimit < 0)
> >> hlimit = ip6_dst_hoplimit(dst);
> >>
> >> - ip6_flow_hdr(hdr, tclass, ip6_make_flowlabel(net, skb, fl6->flowlabel,
> >> - np->autoflowlabel, fl6));
> >> -
> >> hdr->payload_len = htons(seg_len);
> >> hdr->nexthdr = proto;
> >> hdr->hop_limit = hlimit;
> >>
> >
> >
> >We always should initialize hdr and not skip the ip6_flow_hdr call.|
>
> |if np becomes NULL, then anyways hdr won't be initialized due to NULL pointer
> dereference ip6_make_flowlabel.|
Which we would see as a crash. So far no crash has been reported in this
code. Doing a quick code review on the paths leading to ip6_xmit,
inet6_sk must always be set to actually reach up to this point.
Otherwise we would have crashes on all code paths much earler.
Anyway, I would be fine to keep the NULL check in this path, it looks
better because of the inet6_sk you pointed out above but I would
recommend to just use a "np ? np->autoflowlabel :
ip6_default_np_autolabel(net) in the ip6_flow_hdr function.
> |>Do you saw a bug or did you find this by code review? I wonder if np can
> >actually be NULL at this point. Maybe we can just eliminate the NULL check.|
>
> |
>
>
> I must admit that I found it just by code review, and so far didn't face any
> crash whatsoever.
> As we can see in inet6_sk, np could be NULL. Thus, the NULL check seems justified.
Thanks for looking at this!
Bye,
Hannes