Re: [PATCH] [net/ipv6] ip6_output: Add ipv6_pinfo null check

From: Eric Dumazet
Date: Tue Jul 28 2020 - 10:41:40 EST

On 7/27/20 8:12 PM, Cong Wang wrote:
> On Mon, Jul 27, 2020 at 7:14 PM Gaurav Singh <gaurav1086@xxxxxxxxx> wrote:
>> Add return to fix build issue. Haven't reproduced this issue at
>> my end.
>> My hypothesis is this: In function: ip6_xmit(), we have
>> const struct ipv6_pinfo *np = inet6_sk(sk); which returns NULL.
>> Further down the function, there's a check:
>> if (np) hlimit = hp->htop_limit
> This check exists before git history, at that time 'sk' could be NULL,
> hence 'np', so it does not mean it is still necessary now.
> I looked at all callers of ip6_xmit(), I don't see how it is called with
> a non-full socket, neither 'sk' could be NULL after
> commit b30bd282cbf5c46247a279a2e8d2aae027d9f1bf
> ("[IPV6]: ip6_xmit: remove unnecessary NULL ptr check").
> Thanks.


And again, fact that this patch lacks a Fixes: tag speaks for itself.

This means the author expects all reviewers to make a deep analysis.

Please bear with us, and add a Fixes: tag so that we can fully understand what was
the bug origin and why a fix is valid.