Re: [PATCH] dmaengine: pxa_dma: Prefer struct_size over open coded arithmetic
From: Gustavo A. R. Silva <hidden>
Date: 2021-09-21 00:21:49
Also in:
dmaengine, linux-hardening, lkml
On 9/18/21 05:40, Len Baker wrote:
As noted in the "Deprecated Interfaces, Language Features, Attributes, and Conventions" documentation [1], size calculations (especially multiplication) should not be performed in memory allocator (or similar) function arguments due to the risk of them overflowing. This could lead to values wrapping around and a smaller allocation being made than the caller was expecting. Using those allocations could lead to linear overflows of heap memory and other misbehaviors. So, use the struct_size() helper to do the arithmetic instead of the argument "size + count * size" in the kzalloc() function. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments Signed-off-by: Len Baker <redacted>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
quoted hunk ↗ jump to hunk
--- drivers/dma/pxa_dma.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c index 4a2a796e348c..52d04641e361 100644 --- a/drivers/dma/pxa_dma.c +++ b/drivers/dma/pxa_dma.c@@ -742,8 +742,7 @@ pxad_alloc_desc(struct pxad_chan *chan, unsigned int nb_hw_desc) dma_addr_t dma; int i; - sw_desc = kzalloc(sizeof(*sw_desc) + - nb_hw_desc * sizeof(struct pxad_desc_hw *), + sw_desc = kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc), GFP_NOWAIT); if (!sw_desc) return NULL; --2.25.1
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