There are callers that read the unmapped bytes even when rc != 0. Thus, do
not forget to report it in the error path too.

Fixes: 8d40205f6093 ("iommufd: Add kAPI toward external drivers for kernel access")
Cc: stable@vger.kernel.org
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/iommufd/io_pagetable.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c
index 13d010f19ed1..22fc3a12109f 100644
--- a/drivers/iommu/iommufd/io_pagetable.c
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -743,8 +743,10 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start,
 			iommufd_access_notify_unmap(iopt, area_first, length);
 			/* Something is not responding to unmap requests. */
 			tries++;
-			if (WARN_ON(tries > 100))
-				return -EDEADLOCK;
+			if (WARN_ON(tries > 100)) {
+				rc = -EDEADLOCK;
+				goto out_unmapped;
+			}
 			goto again;
 		}
 
@@ -766,6 +768,7 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start,
 out_unlock_iova:
 	up_write(&iopt->iova_rwsem);
 	up_read(&iopt->domains_rwsem);
+out_unmapped:
 	if (unmapped)
 		*unmapped = unmapped_bytes;
 	return rc;
-- 
2.43.0

On Thu, Jun 26, 2025 at 12:34:32PM -0700, Nicolin Chen wrote:
> There are callers that read the unmapped bytes even when rc != 0. Thus, do
> not forget to report it in the error path too.
> 
> Fixes: 8d40205f6093 ("iommufd: Add kAPI toward external drivers for kernel access")
> Cc: stable@vger.kernel.org
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/iommu/iommufd/io_pagetable.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Friday, June 27, 2025 3:35 AM
> 
> There are callers that read the unmapped bytes even when rc != 0. Thus, do
> not forget to report it in the error path too.
> 
> Fixes: 8d40205f6093 ("iommufd: Add kAPI toward external drivers for kernel
> access")
> Cc: stable@vger.kernel.org
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>

Reviewed-by: Kevin Tian <kevin.tian@intel.com>