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* [PATCH v2] iommu: Check if group is NULL before remove device
@ 2021-07-31  7:47 Frank Wunderlich
  2021-08-02 14:23 ` Joerg Roedel
  0 siblings, 1 reply; 2+ messages in thread
From: Frank Wunderlich @ 2021-07-31  7:47 UTC (permalink / raw)
  To: iommu; +Cc: Frank Wunderlich, Joerg Roedel, Will Deacon, linux-kernel, yong.wu

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

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>
---
v2:
- commit-message with captial letters on beginning of sentenence
- added more information, many thanks to Yong Wu
---
 drivers/iommu/iommu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 5419c4b9f27a..63f0af10c403 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. */
-- 
2.25.1


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH v2] iommu: Check if group is NULL before remove device
  2021-07-31  7:47 [PATCH v2] iommu: Check if group is NULL before remove device Frank Wunderlich
@ 2021-08-02 14:23 ` Joerg Roedel
  0 siblings, 0 replies; 2+ messages in thread
From: Joerg Roedel @ 2021-08-02 14:23 UTC (permalink / raw)
  To: Frank Wunderlich
  Cc: iommu, Frank Wunderlich, Will Deacon, linux-kernel, yong.wu

On Sat, Jul 31, 2021 at 09:47:37AM +0200, Frank Wunderlich wrote:
> Fixes: d72e31c93746 ("iommu: IOMMU Groups")
> Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> ---
> v2:
> - commit-message with captial letters on beginning of sentenence
> - added more information, many thanks to Yong Wu

Applied, thanks.

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2021-08-02 14:25 UTC | newest]

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