iommu: iommufd: fix WARNING in iommufd_device_unbind

Fix an issue detected by syzbot:

WARNING in iommufd_device_unbind iommufd: Time out waiting for iommufd object to become free

Resolve a warning in iommufd_device_unbind caused by a timeout while
waiting for the shortterm_users reference count to reach zero. The
existing 10-second timeout is insufficient in some scenarios, resulting in
failures the above warning.

Increase the timeout in iommufd_object_dec_wait_shortterm from 10 seconds
to 60 seconds to allow sufficient time for the reference count to drop to
zero. This change prevents premature timeouts and reduces the likelihood
of warnings during iommufd_device_unbind.

Fixes: 6f9c4d8c468c ("iommufd: Do not UAF during iommufd_put_object()")
Link: https://patch.msgid.link/r/20241123195900.3176-1-surajsonawane0215@gmail.com
Reported-by: syzbot+c92878e123785b1fa2db@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=c92878e123785b1fa2db
Tested-by: syzbot+c92878e123785b1fa2db@syzkaller.appspotmail.com
Signed-off-by: Suraj Sonawane <surajsonawane0215@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 97c5e3567d33e453dea87f85ba42da7f3ad41cf5..d898d05be690fd4661c9ddc3d21560e32fd99358 100644 (file)
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -104,7 +104,7 @@ static int iommufd_object_dec_wait_shortterm(struct iommufd_ctx *ictx,
        if (wait_event_timeout(ictx->destroy_wait,
                                refcount_read(&to_destroy->shortterm_users) ==
                                        0,
-                               msecs_to_jiffies(10000)))
+                               msecs_to_jiffies(60000)))
                return 0;
 
        pr_crit("Time out waiting for iommufd object to become free\n");