Messages in this thread |  | | Date | Mon, 26 Sep 2022 15:50:43 +0200 | Subject | Re: [PATCH v2 13/16] mempool: Use kmalloc_size_roundup() to match ksize() usage | From | Vlastimil Babka <> |
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On 9/23/22 22:28, Kees Cook wrote: > Round up allocations with kmalloc_size_roundup() so that mempool's use > of ksize() is always accurate and no special handling of the memory is > needed by KASAN, UBSAN_BOUNDS, nor FORTIFY_SOURCE. > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: linux-mm@kvack.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > mm/mempool.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/mempool.c b/mm/mempool.c > index 96488b13a1ef..0f3107b28e6b 100644 > --- a/mm/mempool.c > +++ b/mm/mempool.c > @@ -526,7 +526,7 @@ EXPORT_SYMBOL(mempool_free_slab); > */ > void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data) > { > - size_t size = (size_t)pool_data; > + size_t size = kmalloc_size_roundup((size_t)pool_data);
Hm it is kinda wasteful to call into kmalloc_size_roundup for every allocation that has the same input. We could do it just once in mempool_init_node() for adjusting pool->pool_data ?
But looking more closely, I wonder why poison_element() and kasan_unpoison_element() in mm/mempool.c even have to use ksize()/__ksize() and not just operate on the requested size (again, pool->pool_data). If no kmalloc mempool's users use ksize() to write beyond requested size, then we don't have to unpoison/poison that area either?
> return kmalloc(size, gfp_mask); > } > EXPORT_SYMBOL(mempool_kmalloc);
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