diff options
| author | Jacob Pan <jacob.pan@linux.microsoft.com> | 2025-06-18 16:46:18 -0700 |
|---|---|---|
| committer | Alex Williamson <alex.williamson@redhat.com> | 2025-07-11 14:43:38 -0600 |
| commit | 982ddd59ed97dc7e63efd97ed50273ffb817bd41 (patch) | |
| tree | dcaa3b7ca4f1f1bba1c4d605690ed662f7cb9594 | |
| parent | b25e271b377999191b12f0afbe1861edcf57e3fe (diff) | |
vfio: Prevent open_count decrement to negative
When vfio_df_close() is called with open_count=0, it triggers a warning in
vfio_assert_device_open() but still decrements open_count to -1. This allows
a subsequent open to incorrectly pass the open_count == 0 check, leading to
unintended behavior, such as setting df->access_granted = true.
For example, running an IOMMUFD compat no-IOMMU device with VFIO tests
(https://github.com/awilliam/tests/blob/master/vfio-noiommu-pci-device-open.c)
results in a warning and a failed VFIO_GROUP_GET_DEVICE_FD ioctl on the first
run, but the second run succeeds incorrectly.
Add checks to avoid decrementing open_count below zero.
Fixes: 05f37e1c03b6 ("vfio: Pass struct vfio_device_file * to vfio_device_open/close()")
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250618234618.1910456-2-jacob.pan@linux.microsoft.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
| -rw-r--r-- | drivers/vfio/vfio_main.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index 1fd261efc582..5046cae05222 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -583,7 +583,8 @@ void vfio_df_close(struct vfio_device_file *df) lockdep_assert_held(&device->dev_set->lock); - vfio_assert_device_open(device); + if (!vfio_assert_device_open(device)) + return; if (device->open_count == 1) vfio_df_device_last_close(df); device->open_count--; |