[PATCH] iommu: Check return of __iommu_attach_device()

[Shameer Kolothum]

Currently iommu_create_device_direct_mappings() is called
without checking the return of __iommu_attach_device(). This
may result in failures in iommu driver if dev attach returns
error.

Fixes: ce574c27ae27("iommu: Move iommu_group_create_direct_mappings() out of iommu_group_add_device()")
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
Crash log:
[   31.353605] hns3 0000:7d:00.3: Adding to iommu group 10
[   31.358822] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018
[   31.367567] Mem abort info:
[   31.370350]   ESR = 0x96000004
[   31.373391]   EC = 0x25: DABT (current EL), IL = 32 bits
[   31.378680]   SET = 0, FnV = 0
[   31.381720]   EA = 0, S1PTW = 0
[   31.384847] Data abort info:
[   31.387716]   ISV = 0, ISS = 0x00000004
[   31.391535]   CM = 0, WnR = 0
[   31.394491] [0000000000000018] user address but active_mm is swapper
[   31.400818] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[   31.406365] Modules linked in:
[   31.409409] CPU: 21 PID: 1 Comm: swapper/0 Not tainted 5.10.0-rc4-00008-gdd5aba9d719-dirty #79
[   31.417980] Hardware name: Huawei TaiShan 200 (Model 2280)/BC82AMDD, BIOS 2280-V2 CS V3.B220.01 03/19/2020
[   31.427588] pstate: 00c00009 (nzcv daif +PAN +UAO -TCO BTYPE=--)
[   31.433566] pc : arm_smmu_tlb_inv_range+0x178/0x1f0
[   31.438422] lr : arm_smmu_tlb_inv_range+0x5c/0x1f0
[   31.443190] sp : ffff80001043b4e0
...
[   31.531175] Call trace:
[   31.533613]  arm_smmu_tlb_inv_range+0x178/0x1f0
[   31.538122]  arm_smmu_iotlb_sync+0x2c/0x38
[   31.542200]  iommu_unmap+0x60/0x90
[   31.545585]  __iommu_map+0x110/0x1f0
[   31.549144]  iommu_create_device_direct_mappings.isra.34+0x1ac/0x250
[   31.555468]  iommu_probe_device+0x6c/0x110
[   31.559551]  iort_iommu_configure_id+0x114/0x218
[   31.564148]  acpi_dma_configure_id+0x94/0xe0
[   31.568402]  pci_dma_configure+0xc8/0xf0
[   31.572310]  really_probe+0xd4/0x3e0
[   31.575871]  driver_probe_device+0x5c/0xc0

---
 drivers/iommu/iommu.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index b53446bb8c6b..0f4dc25d46c9 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -264,16 +264,18 @@ int iommu_probe_device(struct device *dev)
 	 */
 	iommu_alloc_default_domain(group, dev);
 
-	if (group->default_domain)
+	if (group->default_domain) {
 		ret = __iommu_attach_device(group->default_domain, dev);
+		if (ret) {
+			iommu_group_put(group);
+			goto err_release;
+		}
+	}
 
 	iommu_create_device_direct_mappings(group, dev);
 
 	iommu_group_put(group);
 
-	if (ret)
-		goto err_release;
-
 	if (ops->probe_finalize)
 		ops->probe_finalize(dev);
 
-- 
2.17.1