Re: [PATCH 0/3] Fix a race with fput during eventq abort

Jason Gunthorpe
2025-09-19T13:43:35Z

On Wed, Sep 17, 2025 at 05:01:46PM -0300, Jason Gunthorpe wrote:
> Syzkaller found this, fput runs the release from a work queue so the
> refcount remains elevated during abort. This is tricky so move more
> handling of files into the core code.
>
> Add a WARN_ON to catch things like this more reliably without relying on
> kasn.
>
> Update the fail_nth test to succeed on 6.17 kernels.
>
> Jason Gunthorpe (3):
> iommufd: Fix race during abort for file descriptors
> iommufd: WARN if an object is aborted with an elevated refcount
> iommufd/selftest: Update the fail_nth limit
>
> drivers/iommu/iommufd/device.c | 3 +-
> drivers/iommu/iommufd/eventq.c | 9 +----
> drivers/iommu/iommufd/iommufd_private.h | 3 +-
> drivers/iommu/iommufd/main.c | 39 +++++++++++++++++--
> .../selftests/iommu/iommufd_fail_nth.c | 2 +-
> 5 files changed, 42 insertions(+), 14 deletions(-)

Applied to for-rc

Jason