Re: tvb allocator (was: Re: [Wireshark-commits] master b6d20a2: Optimize reseting epan_dissect_t when filtering.)

[Bálint Réczey <balint () balintreczey hu>]

2014-07-24 20:48 GMT+02:00 Evan Huus <eapache () gmail com>:
> On Thu, Jul 24, 2014 at 2:42 PM, Bálint Réczey <balint () balintreczey hu>
> wrote:
> > Hi Jakub,
> >
> > 2014-07-22 0:52 GMT+02:00  <darkjames-ws () darkjames pl>:
> > > Hi,
> > >
> > > On Sat, Jul 12, 2014 at 02:27:06AM +0200, B??lint R??czey wrote:
> > > > I plan using ASAN for all programs which would catch (among others)
> > > > use-after-free and reading below or over the malloc()-ed
> > > > memory area. Those can't be caught if the program uses another layer
> > > > of bulk memory allocations.
> > > > g_malloc() and g_slice_* has the same problem, but they can be
> > > > overrideb by passing G_SLICE=always-malloc .
> > >
> > > We have these environment variables also, ver{3, 4} introduce
> > > WIRESHARK_DEBUG_WMEM_OBJECT_POOL_SKIP,
> > > where you can set, and object pool will not maintain free list of
> > > objects.
> > >
> > > I see no problem with enabling it by default when building with ASAN.
> > >
> > > Also it should be quite easy to use ASAN manual poisoning[1] with object
> > > pool API.
> > >
> > > wmem_object_pool_alloc(wmem_allocator_t *allocator, wmem_object_pool_t
> > > *pool):
> > >     if (pool->current_count > 0) {
> > >         ...
> > >         ASAN_UNPOISON_MEMORY_REGION(pool->free_list, pool->object_size);
> > >         pool->free_list = pool->free_list->next;
> > >
> > > wmem_object_pool_free(wmem_allocator_t *allocator, wmem_object_pool_t
> > > *pool, void *ptr)
> > >     ...
> > >     ASAN_POISON_MEMORY_REGION(ptr, pool->object_size);
> > >
> > > (not tested).
> > Thank you, I was not aware of those macros. I think we should add
> > those to the custom allocator code.
>
>
> Just setting WIRESHARK_DEBUG_WMEM_OVERRIDE=simple is easier, is it not?
I think it would worth testing the performance of both options, but
yes, using the simple allocator seems to be easier.
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