* [PATCH] dmaengine: stm32-dma: Use struct_size() helper
@ 2019-08-30 16:14 Gustavo A. R. Silva
2019-09-04 4:55 ` Vinod Koul
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2019-08-30 16:14 UTC (permalink / raw)
To: Vinod Koul, Dan Williams, Maxime Coquelin, Alexandre Torgue
Cc: dmaengine, linux-stm32, linux-arm-kernel, linux-kernel,
Gustavo A. R. Silva, Kees Cook
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:
struct stm32_dma_desc {
...
struct stm32_dma_sg_req sg_req[];
};
Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.
So, replace the following function:
static struct stm32_dma_desc *stm32_dma_alloc_desc(u32 num_sgs)
{
return kzalloc(sizeof(struct stm32_dma_desc) +
sizeof(struct stm32_dma_sg_req) * num_sgs, GFP_NOWAIT);
}
with:
kzalloc(struct_size(desc, sg_req, num_sgs), GFP_NOWAIT)
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/dma/stm32-dma.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index e4cbe38d1b83..5989b0893521 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -243,12 +243,6 @@ static void stm32_dma_write(struct stm32_dma_device *dmadev, u32 reg, u32 val)
writel_relaxed(val, dmadev->base + reg);
}
-static struct stm32_dma_desc *stm32_dma_alloc_desc(u32 num_sgs)
-{
- return kzalloc(sizeof(struct stm32_dma_desc) +
- sizeof(struct stm32_dma_sg_req) * num_sgs, GFP_NOWAIT);
-}
-
static int stm32_dma_get_width(struct stm32_dma_chan *chan,
enum dma_slave_buswidth width)
{
@@ -853,7 +847,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_slave_sg(
return NULL;
}
- desc = stm32_dma_alloc_desc(sg_len);
+ desc = kzalloc(struct_size(desc, sg_req, sg_len), GFP_NOWAIT);
if (!desc)
return NULL;
@@ -954,7 +948,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_cyclic(
num_periods = buf_len / period_len;
- desc = stm32_dma_alloc_desc(num_periods);
+ desc = kzalloc(struct_size(desc, sg_req, num_periods), GFP_NOWAIT);
if (!desc)
return NULL;
@@ -989,7 +983,7 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
int i;
num_sgs = DIV_ROUND_UP(len, STM32_DMA_ALIGNED_MAX_DATA_ITEMS);
- desc = stm32_dma_alloc_desc(num_sgs);
+ desc = kzalloc(struct_size(desc, sg_req, num_sgs), GFP_NOWAIT);
if (!desc)
return NULL;
--
2.23.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] dmaengine: stm32-dma: Use struct_size() helper
2019-08-30 16:14 [PATCH] dmaengine: stm32-dma: Use struct_size() helper Gustavo A. R. Silva
@ 2019-09-04 4:55 ` Vinod Koul
0 siblings, 0 replies; 2+ messages in thread
From: Vinod Koul @ 2019-09-04 4:55 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Dan Williams, Maxime Coquelin, Alexandre Torgue, dmaengine,
linux-stm32, linux-arm-kernel, linux-kernel, Kees Cook
On 30-08-19, 11:14, Gustavo A. R. Silva wrote:
> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
>
> struct stm32_dma_desc {
> ...
> struct stm32_dma_sg_req sg_req[];
> };
>
>
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes.
>
> So, replace the following function:
>
> static struct stm32_dma_desc *stm32_dma_alloc_desc(u32 num_sgs)
> {
> return kzalloc(sizeof(struct stm32_dma_desc) +
> sizeof(struct stm32_dma_sg_req) * num_sgs, GFP_NOWAIT);
> }
>
> with:
>
> kzalloc(struct_size(desc, sg_req, num_sgs), GFP_NOWAIT)
>
> This code was detected with the help of Coccinelle.
Applied, thanks
--
~Vinod
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