Messages in this thread Patch in this message | | | Date | Tue, 20 Dec 2022 19:46:32 +0530 | From | Deepak R Varma <> | Subject | [PATCH v2] ARM/dma-mapping: use kvcalloc for fallback memory allocation need |
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Current conditional determination of whether to use kzalloc or vzalloc has known issues such as "indefinite retry" when less than PAGE_SIZE memory is needed, but is unavailable. This LWN article [1] describes these issues in greater detail. Use helper function kvcalloc() instead which is more efficient in terms of performance and security.
[1] https://lwn.net/Articles/711653/
This patch proposal is based on following Coccinelle warning using the kvmalloc.cocci semantic patch. arch/arm/mm/dma-mapping.c:858:28-29: WARNING opportunity for kvmalloc
The semantic patch suggests using kvzalloc() helper function, however, this patch proposes to use kvcalloc instead. kvcalloc() helper function uses 2-factor argument form which is better from a security perspective as described in the following KSPP project commit.
Commit 4e3fd7217105 ("wireguard: ratelimiter: use kvcalloc() instead of kvzalloc()")
Signed-off-by: Deepak R Varma <drv@mailo.com> ---
Changes in v2: 1. Update patch subject to use kvcalloc 2. Use kvcalloc instead of kvzalloc helper function. Revise the patch proposal and the patch description accordingly.
arch/arm/mm/dma-mapping.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index c135f6e37a00..35092ecd30e1 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -851,14 +851,10 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size, { struct page **pages; int count = size >> PAGE_SHIFT; - int array_size = count * sizeof(struct page *); int i = 0; int order_idx = 0;
- if (array_size <= PAGE_SIZE) - pages = kzalloc(array_size, GFP_KERNEL); - else - pages = vzalloc(array_size); + pages = kvcalloc(count, sizeof(struct page *), GFP_KERNEL); if (!pages) return NULL;
-- 2.34.1
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