linux-kernel - Re: [PATCH] dma: idxd: cdev: Fix uninitialized use of sva in idxd_cdev

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Message-ID: <d39d0480-0bf6-4e8a-8bf1-b18011bc32ac@gmail.com>
Date: Fri, 11 Apr 2025 01:26:07 +0530
From: Purva Yeshi <purvayeshi550@...il.com>
To: Vinicius Costa Gomes <vinicius.gomes@...el.com>, dave.jiang@...el.com,
 vkoul@...nel.org
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dma: idxd: cdev: Fix uninitialized use of sva in
 idxd_cdev_open

On 11/04/25 01:10, Vinicius Costa Gomes wrote:
> Purva Yeshi <purvayeshi550@...il.com> writes:
> 
>> Fix Smatch-detected issue:
>> drivers/dma/idxd/cdev.c:321 idxd_cdev_open() error:
>> uninitialized symbol 'sva'.
>>
>> 'sva' pointer may be used uninitialized in error handling paths.
>> Specifically, if PASID support is enabled and iommu_sva_bind_device()
>> returns an error, the code jumps to the cleanup label and attempts to
>> call iommu_sva_unbind_device(sva) without ensuring that sva was
>> successfully assigned. This triggers a Smatch warning about an
>> uninitialized symbol.
>>
>> Initialize sva to NULL at declaration and add a check using
>> IS_ERR_OR_NULL() before unbinding the device. This ensures the
>> function does not use an invalid or uninitialized pointer during
>> cleanup.
>>
>> Signed-off-by: Purva Yeshi <purvayeshi550@...il.com>
>> ---
>>   drivers/dma/idxd/cdev.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
>> index ff94ee892339..7bd031a60894 100644
>> --- a/drivers/dma/idxd/cdev.c
>> +++ b/drivers/dma/idxd/cdev.c
>> @@ -222,7 +222,7 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
>>   	struct idxd_wq *wq;
>>   	struct device *dev, *fdev;
>>   	int rc = 0;
>> -	struct iommu_sva *sva;
>> +	struct iommu_sva *sva = NULL;
>>   	unsigned int pasid;
>>   	struct idxd_cdev *idxd_cdev;
>>   
>> @@ -317,7 +317,7 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
>>   	if (device_user_pasid_enabled(idxd))
>>   		idxd_xa_pasid_remove(ctx);
>>   failed_get_pasid:
>> -	if (device_user_pasid_enabled(idxd))
>> +	if (device_user_pasid_enabled(idxd) && !IS_ERR_OR_NULL(sva))
> 
> Optional: I would change this to only checking for the validity of
> 'sva', the other condition would be true if 'sva' is valid.
> 
> But for consistency with the condition above, I am not opposed to the
> way this patch is written:
> 
> Acked-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
> 
> 
> Cheers,

Hi Vinicius,

Thank you for the review and the Acked-by tag.
I appreciate your feedback on the conditional check.

Best regards,
Purva