On Mon, Sep 26, 2022 at 03:50:43PM +0200, Vlastimil Babka wrote:
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?
Yeah, I think that's a fair point. I will adjust this.