2023-01-03 06:41:18

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.
Also an empty @owner is a more serious problem than refcount leak.
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]>
---
changes in v2:
- Remove set NULL to group as suggested by Baolu Lu.
- Update commit message according to Lu's explanation.
---
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..5f6a85aea501 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;
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 23:35:43

by Jason Gunthorpe

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

On Tue, Jan 03, 2023 at 10:30:17AM +0400, Miaoqian Lin wrote:
> iommu_group_get() returns the group with the reference incremented.
> Also an empty @owner is a more serious problem than refcount leak.
> 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]>
> ---
> changes in v2:
> - Remove set NULL to group as suggested by Baolu Lu.
> - Update commit message according to Lu's explanation.
> ---
> drivers/iommu/iommu.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)

Reviewed-by: Jason Gunthorpe <[email protected]>

Joerg, can you pick this for rc?

Thanks,
Jason