[PATCH] vfio: selftests: fix crash in vfio_dma_mapping_mmio_test

[Alex Mastro <amastro@fb.com>]

Remove the __iommu_unmap() call on a region that was never mapped.
When __iommu_map() fails (expected for MMIO vaddrs in non-VFIO
modes), the region is not added to the dma_regions list, leaving its
list_head zero-initialized. If the unmap ioctl returns success,
__iommu_unmap() calls list_del_init() on this zeroed node and crashes.

This fixes the iommufd_compat_type1 and iommufd_compat_type1v2
test variants.

Fixes: 080723f4d4c3 ("vfio: selftests: Add vfio_dma_mapping_mmio_test")
Signed-off-by: Alex Mastro <amastro@fb.com>
---
The bug was missed because the test was originally run against a kernel
without commit afb47765f923 ("iommufd: Make vfio_compat's unmap succeed
if the range is already empty"). Without that fix, the unmap ioctl
returned -ENOENT, taking the early return before list_del_init().
---
 tools/testing/selftests/vfio/vfio_dma_mapping_mmio_test.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/testing/selftests/vfio/vfio_dma_mapping_mmio_test.c b/tools/testing/selftests/vfio/vfio_dma_mapping_mmio_test.c
index 957a89ce7b3a..d7f25ef77671 100644
--- a/tools/testing/selftests/vfio/vfio_dma_mapping_mmio_test.c
+++ b/tools/testing/selftests/vfio/vfio_dma_mapping_mmio_test.c
@@ -100,7 +100,6 @@ static void do_mmio_map_test(struct iommu *iommu,
 		iommu_unmap(iommu, &region);
 	} else {
 		VFIO_ASSERT_NE(__iommu_map(iommu, &region), 0);
-		VFIO_ASSERT_NE(__iommu_unmap(iommu, &region, NULL), 0);
 	}
 }
 

---
base-commit: 96ca4caf9066f5ebd35b561a521af588a8eb0215
change-id: 20260303-fix-mmio-test-d3bd688105f3

Best regards,
-- 
Alex Mastro <amastro@fb.com>