Re: [PATCH] dmaengine: idxd: Fix potential null dereference on pointer status

[Dave Jiang <dave.jiang@intel.com>]

On 4/15/2021 4:06 AM, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> There are calls to idxd_cmd_exec that pass a null status pointer however
> a recent commit has added an assignment to *status that can end up
> with a null pointer dereference.  The function expects a null status
> pointer sometimes as there is a later assignment to *status where
> status is first null checked.  Fix the issue by null checking status
> before making the assignment.
>
> Addresses-Coverity: ("Explicit null dereferenced")
> Fixes: 89e3becd8f82 ("dmaengine: idxd: check device state before issue command")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Acked-by: Dave Jiang <dave.jiang@intel.com>

Thanks!

> ---
>   drivers/dma/idxd/device.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 31c819544a22..78d2dc5e9bd8 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -451,7 +451,8 @@ static void idxd_cmd_exec(struct idxd_device *idxd, int cmd_code, u32 operand,
>   
>   	if (idxd_device_is_halted(idxd)) {
>   		dev_warn(&idxd->pdev->dev, "Device is HALTED!\n");
> -		*status = IDXD_CMDSTS_HW_ERR;
> +		if (status)
> +			*status = IDXD_CMDSTS_HW_ERR;
>   		return;
>   	}
>