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982ddd59ed
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: 05f37e1c03 ("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.