[RESEND,v3] ARM/dma-mapping: use kvcalloc for fallback memory allocation need
Commit Message
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 v3:
1. Use updated maintainer list to send the patch.
Suggested by "Russell King (Oracle)" <linux@armlinux.org.uk>
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(-)
@@ -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;