2022-12-30 08:42:20

by Miaoqian Lin

Subject: [PATCH] iommu: Fix refcount leak in iommu_device_claim_dma_owner

iommu_group_get() returns the group with the reference incremented.
Move iommu_group_get() after owner check to fix the refcount leak.

Fixes: 89395ccedbc1 ("iommu: Add device-centric DMA ownership interfaces")
Signed-off-by: Miaoqian Lin <[email protected]>
---
drivers/iommu/iommu.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index de91dd88705b..3a7dd8b61fab 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3185,14 +3185,16 @@ EXPORT_SYMBOL_GPL(iommu_group_claim_dma_owner);
*/
int iommu_device_claim_dma_owner(struct device *dev, void *owner)
{
- struct iommu_group *group = iommu_group_get(dev);
+ struct iommu_group *group = NULL;
int ret = 0;

- if (!group)
- return -ENODEV;
if (WARN_ON(!owner))
return -EINVAL;

+ group = iommu_group_get(dev);
+ if (!group)
+ return -ENODEV;
+
mutex_lock(&group->mutex);
if (group->owner_cnt) {
if (group->owner != owner) {
--
2.25.1

2023-01-03 01:46:09

by Baolu Lu

Subject: Re: [PATCH] iommu: Fix refcount leak in iommu_device_claim_dma_owner

On 12/30/22 4:31 PM, Miaoqian Lin wrote:
> iommu_group_get() returns the group with the reference incremented.
> Move iommu_group_get() after owner check to fix the refcount leak.

An empty @owner is a more serious problem than refcount leak. It should
not happen, so a WARN_ON() was added there.

Anyway, your change makes the code better.

>
> Fixes: 89395ccedbc1 ("iommu: Add device-centric DMA ownership interfaces")
> Signed-off-by: Miaoqian Lin <[email protected]>
> ---
> drivers/iommu/iommu.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index de91dd88705b..3a7dd8b61fab 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -3185,14 +3185,16 @@ EXPORT_SYMBOL_GPL(iommu_group_claim_dma_owner);
> */
> int iommu_device_claim_dma_owner(struct device *dev, void *owner)
> {
> - struct iommu_group *group = iommu_group_get(dev);
> + struct iommu_group *group = NULL;

No need to set NULL to group.

> int ret = 0;
>
> - if (!group)
> - return -ENODEV;
> if (WARN_ON(!owner))
> return -EINVAL;
>
> + group = iommu_group_get(dev);
> + if (!group)
> + return -ENODEV;
> +
> mutex_lock(&group->mutex);
> if (group->owner_cnt) {
> if (group->owner != owner) {

Others look good to me.

Reviewed-by: Lu Baolu <[email protected]>

--
Best regards,
baolu

2023-01-13 13:54:36

by Joerg Roedel

Subject: Re: [PATCH] iommu: Fix refcount leak in iommu_device_claim_dma_owner

On Fri, Dec 30, 2022 at 12:31:00PM +0400, Miaoqian Lin wrote:
> iommu_group_get() returns the group with the reference incremented.
> Move iommu_group_get() after owner check to fix the refcount leak.
>
> Fixes: 89395ccedbc1 ("iommu: Add device-centric DMA ownership interfaces")
> Signed-off-by: Miaoqian Lin <[email protected]>
> ---
> drivers/iommu/iommu.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)

Applied for 6.2, thanks.