linux-kernel - Re: [PATCH] dmaengine: idxd: Fix passing freed memory in idxd_cdev

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Date:   Tue, 9 May 2023 08:13:42 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
Cc:     error27@...il.com, kernel-janitors@...r.kernel.org,
        dan.carpenter@...aro.org, Fenghua Yu <fenghua.yu@...el.com>,
        Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: idxd: Fix passing freed memory in
 idxd_cdev_open()



On 5/8/23 11:07 PM, Harshit Mogalapalli wrote:
> Smatch warns:
> 	drivers/dma/idxd/cdev.c:327:
> 		idxd_cdev_open() warn: 'sva' was already freed.
> 
> When idxd_wq_set_pasid() fails, the current code unbinds sva and then
> goes to 'failed_set_pasid' where iommu_sva_unbind_device is called
> again causing the above warning.
> [ device_user_pasid_enabled(idxd) is still true when calling
> failed_set_pasid ]
> 
> Fix this by removing additional unbind when idxd_wq_set_pasid() fails
> 
> Fixes: b022f59725f0 ("dmaengine: idxd: add idxd_copy_cr() to copy user completion record during page fault handling")
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>

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

Thank you!
> ---
> This is purely based on static analysis. Only compile tested.
> ---
>   drivers/dma/idxd/cdev.c | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
> index ecbf67c2ad2b..d32deb9b4e3d 100644
> --- a/drivers/dma/idxd/cdev.c
> +++ b/drivers/dma/idxd/cdev.c
> @@ -277,7 +277,6 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
>   		if (wq_dedicated(wq)) {
>   			rc = idxd_wq_set_pasid(wq, pasid);
>   			if (rc < 0) {
> -				iommu_sva_unbind_device(sva);
>   				dev_err(dev, "wq set pasid failed: %d\n", rc);
>   				goto failed_set_pasid;
>   			}