[PATCH] gpu: host1x: Fix passing zero to ERR_PTR in host1x_iommu_attach()

[Alper Ak]

When iommu_attach_group() returns -ENODEV, the code sets err to 0 but
still falls through to the error path, returning ERR_PTR(0).

Returning ERR_PTR(0) evaluates to NULL and breaks the ERR_PTR/IS_ERR
contract, causing the error to be silently ignored and potentially
leading to NULL pointer dereferences by callers.

Fix this by returning NULL when err is zero, and ERR_PTR(err) only
for actual error codes.

This issue was reported by the Smatch static analyzer.

Fixes: 06867a362de0 ("gpu: host1x: Set DMA mask based on IOMMU setup")
Signed-off-by: Alper Ak <alperyasinak1@xxxxxxxxx>
---
 drivers/gpu/host1x/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index 3f475f0e6545..46a570b861ac 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -450,7 +450,7 @@ static struct iommu_domain *host1x_iommu_attach(struct host1x *host)
 	iommu_group_put(host->group);
 	host->group = NULL;
 
-	return ERR_PTR(err);
+	return err ? ERR_PTR(err) : NULL;
 }
 
 static int host1x_iommu_init(struct host1x *host)
-- 
2.43.0