[PATCH 5.13 030/127] iommu: Check if group is NULL before remove device

Sasha Levin
2021-08-24T16:57:46Z

From: Frank Wunderlich <frank-w@public-files.de>

[ Upstream commit 5aa95d8834e07907e64937d792c12ffef7fb271f ]

If probe_device is failing, iommu_group is not initialized because
iommu_group_add_device is not reached, so freeing it will result
in NULL pointer access.

iommu_bus_init
->bus_iommu_probe
->probe_iommu_group in for each:/* return -22 in fail case */
->iommu_probe_device
->__iommu_probe_device /* return -22 here.*/
-> ops->probe_device /* return -22 here.*/
-> iommu_group_get_for_dev
-> ops->device_group
-> iommu_group_add_device //good case
->remove_iommu_group //in fail case, it will remove group
->iommu_release_device
->iommu_group_remove_device // here we don't have group

In my case ops->probe_device (mtk_iommu_probe_device from
mtk_iommu_v1.c) is due to failing fwspec->ops mismatch.

Fixes: d72e31c93746 ("iommu: IOMMU Groups")
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Link: https://lore.kernel.org/r/20210731074737.4573-1-linux@fw-web.de
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iommu/iommu.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 808ab70d5df5..db966a7841fe 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -924,6 +924,9 @@ void iommu_group_remove_device(struct device *dev)
struct iommu_group *group = dev->iommu_group;
struct group_device *tmp_device, *device = NULL;

+ if (!group)
+ return;
+
dev_info(dev, "Removing from iommu group %d\n", group->id);

/* Pre-notify listeners that a device is being removed. */
--
2.30.2