Re: [PATCH 6/6] kasan: improve double-free reports.

Alexander Potapenko
2016-08-02T12:57:05Z

On Tue, Aug 2, 2016 at 2:34 PM, Andrey Ryabinin <aryabinin@virtuozzo.com> wrote:
>
>
> On 08/02/2016 02:39 PM, Alexander Potapenko wrote:
>
>>> +static void kasan_end_report(unsigned long *flags)
>>> +{
>>> + pr_err("==================================================================\n");
>>> + add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
>> Don't we want to add the taint as early as possible once we've
>> detected the error?
>
> What for?
> It certainly shouldn't be before dump_stack(), otherwise on the first report the kernel will claimed as tainted.
Ah, got it. Fair enough.
>
>>>
>>> +void kasan_report_double_free(struct kmem_cache *cache, void *object,
>>> + s8 shadow)
>>> +{
>>> + unsigned long flags;
>>> +
>>> + kasan_start_report(&flags);
>>> + pr_err("BUG: Double free or corrupt pointer\n");
>> How about "Double free or freeing an invalid pointer\n"?
>> I think "corrupt pointer" doesn't exactly reflect where the bug is.
>
> Ok
>

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Alexander Potapenko
Software Engineer

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