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

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Message-ID: <4e545597-8fe5-411d-6bb7-0c5e8eea5b23@intel.com>
Date:   Thu, 15 Apr 2021 07:09:40 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     Colin King <colin.king@...onical.com>,
        Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: idxd: Fix potential null dereference on
 pointer status


On 4/15/2021 4:06 AM, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.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@...onical.com>

Acked-by: Dave Jiang <dave.jiang@...el.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;
>   	}
>