[PATCH] spi: stm32: fix NULL check on pointer-to-pointer variable
Antonio Quartulli
antonio at mandelbit.com
Mon Jun 30 00:48:44 PDT 2025
Hi Clement,
On 30/06/2025 09:34, Clement LE GOFFIC wrote:
> Hi Antonio,
>
> On 6/28/25 02:02, Antonio Quartulli wrote:
>> In stm32_spi_prepare_rx_dma_mdma_chaining() both rx_dma_desc
>> and rx_mdma_desc are passed as pointer-to-pointer arguments.
>>
>> The goal is to pass back to the caller the value returned
>> by dmaengine_prep_slave_sg(), when it is not NULL.
>>
>> However, the NULL check on the result is erroneously
>> performed without dereferencing the pointer.
>>
>> Add the proper dereference operator to both checks.
>>
>> Fixes: d17dd2f1d8a1 ("spi: stm32: use STM32 DMA with STM32 MDMA to
>> enhance DDR use")
>> Addresses-Coverity-ID: 1644715 ("Null pointer dereferences
>> (REVERSE_INULL)")
>> Signed-off-by: Antonio Quartulli <antonio at mandelbit.com>
>> ---
>> drivers/spi/spi-stm32.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
>> index 3d20f09f1ae7..e9fa17e52fb0 100644
>> --- a/drivers/spi/spi-stm32.c
>> +++ b/drivers/spi/spi-stm32.c
>> @@ -1529,7 +1529,7 @@ static int
>> stm32_spi_prepare_rx_dma_mdma_chaining(struct stm32_spi *spi,
>> DMA_PREP_INTERRUPT);
>> sg_free_table(&dma_sgt);
>> - if (!rx_dma_desc)
>> + if (!*rx_dma_desc)
>> return -EINVAL;
>> /* Prepare MDMA slave_sg transfer MEM_TO_MEM (SRAM>DDR) */
>> @@ -1563,8 +1563,8 @@ static int
>> stm32_spi_prepare_rx_dma_mdma_chaining(struct stm32_spi *spi,
>> DMA_PREP_INTERRUPT);
>> sg_free_table(&mdma_sgt);
>> - if (!rx_mdma_desc) {
>> - rx_dma_desc = NULL;
>> + if (!*rx_mdma_desc) {
>> + *rx_dma_desc = NULL;
>> return -EINVAL;
>> }
>
> Good catch for both pointers !
>
> For readability, I would suggest to define two dma_async_tx_descriptor
> ptr at the beginning of the function such as :
> struct dma_async_tx_descriptor *_mdma_desc = *rx_mdma_desc;
> struct dma_async_tx_descriptor *_dma_desc = *rx_dma_desc;
>
> And then use them all along the function even in the assignation.
>
Thanks for the comment.
Will send v2!
Regards,
--
Antonio Quartulli
CEO and Co-Founder
Mandelbit Srl
https://www.mandelbit.com
More information about the linux-arm-kernel
mailing list