All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH] dma-iommu: Add a check to avoid dereference null pointer in function iommu_dma_map_sg()
@ 2021-05-21  3:05 chenxiang
  2021-05-21 10:36 ` Robin Murphy
  0 siblings, 1 reply; 3+ messages in thread
From: chenxiang @ 2021-05-21  3:05 UTC (permalink / raw)
  To: robin.murphy, will, joro, hch; +Cc: iommu, linuxarm, linuxarm

From: Xiang Chen <chenxiang66@hisilicon.com>

The issue is reported by tool TscanCode, and it is possible to deference
null pointer when prev is NULL which is the initial value.

Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
---
 drivers/iommu/dma-iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 4cb63b2..88a4f34 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1042,7 +1042,7 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
 		 *   iova_len == 0, thus we cannot dereference prev the first
 		 *   time through here (i.e. before it has a meaningful value).
 		 */
-		if (pad_len && pad_len < s_length - 1) {
+		if (prev && pad_len && pad_len < s_length - 1) {
 			prev->length += pad_len;
 			iova_len += pad_len;
 		}
-- 
2.8.1

_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] dma-iommu: Add a check to avoid dereference null pointer in function iommu_dma_map_sg()
  2021-05-21  3:05 [PATCH] dma-iommu: Add a check to avoid dereference null pointer in function iommu_dma_map_sg() chenxiang
@ 2021-05-21 10:36 ` Robin Murphy
  2021-05-21 12:34   ` chenxiang (M)
  0 siblings, 1 reply; 3+ messages in thread
From: Robin Murphy @ 2021-05-21 10:36 UTC (permalink / raw)
  To: chenxiang, will, joro, hch; +Cc: iommu, linuxarm, linuxarm

On 2021-05-21 04:05, chenxiang wrote:
> From: Xiang Chen <chenxiang66@hisilicon.com>
> 
> The issue is reported by tool TscanCode, and it is possible to deference
> null pointer when prev is NULL which is the initial value.

No it isn't. This is literally explained in the comment visible in the 
diff context below...

Robin.

> Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
> ---
>   drivers/iommu/dma-iommu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 4cb63b2..88a4f34 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -1042,7 +1042,7 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
>   		 *   iova_len == 0, thus we cannot dereference prev the first
>   		 *   time through here (i.e. before it has a meaningful value).
>   		 */
> -		if (pad_len && pad_len < s_length - 1) {
> +		if (prev && pad_len && pad_len < s_length - 1) {
>   			prev->length += pad_len;
>   			iova_len += pad_len;
>   		}
> 
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] dma-iommu: Add a check to avoid dereference null pointer in function iommu_dma_map_sg()
  2021-05-21 10:36 ` Robin Murphy
@ 2021-05-21 12:34   ` chenxiang (M)
  0 siblings, 0 replies; 3+ messages in thread
From: chenxiang (M) @ 2021-05-21 12:34 UTC (permalink / raw)
  To: Robin Murphy, will, joro, hch; +Cc: iommu, linuxarm, linuxarm



在 2021/5/21 18:36, Robin Murphy 写道:
> On 2021-05-21 04:05, chenxiang wrote:
>> From: Xiang Chen <chenxiang66@hisilicon.com>
>>
>> The issue is reported by tool TscanCode, and it is possible to deference
>> null pointer when prev is NULL which is the initial value.
>
> No it isn't. This is literally explained in the comment visible in the 
> diff context below...
>
> Robin.

ok, thanks

>
>> Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
>> ---
>>   drivers/iommu/dma-iommu.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>> index 4cb63b2..88a4f34 100644
>> --- a/drivers/iommu/dma-iommu.c
>> +++ b/drivers/iommu/dma-iommu.c
>> @@ -1042,7 +1042,7 @@ static int iommu_dma_map_sg(struct device *dev, 
>> struct scatterlist *sg,
>>            *   iova_len == 0, thus we cannot dereference prev the first
>>            *   time through here (i.e. before it has a meaningful 
>> value).
>>            */
>> -        if (pad_len && pad_len < s_length - 1) {
>> +        if (prev && pad_len && pad_len < s_length - 1) {
>>               prev->length += pad_len;
>>               iova_len += pad_len;
>>           }
>>
>
> .
>


_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-05-21 12:34 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-05-21  3:05 [PATCH] dma-iommu: Add a check to avoid dereference null pointer in function iommu_dma_map_sg() chenxiang
2021-05-21 10:36 ` Robin Murphy
2021-05-21 12:34   ` chenxiang (M)

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.