Re: [PATCH 02/12] skbuff: Proactively round up to kmalloc bucket size
From: Jakub Kicinski <kuba@kernel.org>
Date: 2022-09-22 19:40:46
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dri-devel, intel-wired-lan, linux-btrfs, linux-fsdevel, linux-hardening, linux-media, linux-mm, linux-wireless, lkml, llvm
On Wed, 21 Sep 2022 20:10:03 -0700 Kees Cook wrote:
quoted hunk ↗ jump to hunk
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 974bbbbe7138..4fe4c7544c1d 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c@@ -427,14 +427,15 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask, */ size = SKB_DATA_ALIGN(size); size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); - data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc); - if (unlikely(!data)) - goto nodata; - /* kmalloc(size) might give us more room than requested. + /* kmalloc(size) might give us more room than requested, so + * allocate the true bucket size up front. * Put skb_shared_info exactly at the end of allocated zone, * to allow max possible filling before reallocation. */ - osize = ksize(data); + osize = kmalloc_size_roundup(size); + data = kmalloc_reserve(osize, gfp_mask, node, &pfmemalloc); + if (unlikely(!data)) + goto nodata; size = SKB_WITH_OVERHEAD(osize); prefetchw(data + size);
I'd rename osize here to alloc_size for consistency but one could argue either way :) Acked-by: Jakub Kicinski <kuba@kernel.org>