From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] netlink: don't copy over empty attribute data
Date: Sun, 26 Oct 2014 22:03:50 -0400 (EDT)
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Cc: a.ryabinin@samsung.com, pablo@netfilter.org, mschmidt@redhat.com,
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To: sasha.levin@oracle.com
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From: Sasha Levin <sasha.levin@oracle.com>
Date: Sun, 26 Oct 2014 19:32:42 -0400

> How so? GCC states clearly that you should *never* pass a NULL
> pointer there:
> 
> "The pointers passed to memmove (and similar functions in <string.h>) must
> be non-null even when nbytes==0" (https://gcc.gnu.org/gcc-4.9/porting_to.html).
> 
> Even if it doesn't dereference it, it can break somehow in a subtle way. Leaving
> the kernel code assuming that gcc (or any other compiler) would always behave
> the same in a situation that shouldn't occur.

Show me a legal way in which one could legally dereference the pointer
when length is zero, and I'll entertain this patch.