Re: [PATCH v2 13/16] mempool: Use kmalloc_size_roundup() to match ksize() usage
From: Vlastimil Babka <hidden>
Date: 2022-09-26 15:12:32
Also in:
dri-devel, intel-wired-lan, linux-btrfs, linux-fsdevel, linux-hardening, linux-media, linux-mm, lkml, llvm
On 9/23/22 22:28, Kees Cook wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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);