[PATCH v1 0/7] iommufd: Fix bugs in eventq fops_read paths

[Nicolin Chen <nicolinc@nvidia.com>]

Bugs were found in iommufd_veventq/fault_fops_read(), where userspace may:
 - Receive a corrupted byte stream after a partial copy_to_user
 - Spin in a poll/read loop when reading with an undersized buffer
 - Miss notifications when the kernel cannot allocate a lost-events copy
 - Receive duplicate faults with stale cookies after a mid-group failure
 - Cause the kernel to retry the same failed copy_to_user indefinitely

Fix them, then add selftest coverage for the vEVENTQ count validation.

This is on github:
https://github.com/nicolinc/iommufd/commits/fix_eventq_read_bugs-v1

Rebased on Jason's for-next tree with the veventq_depth series applied.

Nicolin Chen (7):
  iommufd: Rewind header length in done if iommufd_veventq_fops_read()
    fails
  iommufd: Reject invalid read count in iommufd_veventq_fops_read()
  iommufd: Propagate allocation failure in
    iommufd_veventq_deliver_fetch()
  iommufd: Reject invalid read count in iommufd_fault_fops_read()
  iommufd: Break the loop on failure in iommufd_fault_fops_read()
  iommufd: Avoid partial fault group delivery in
    iommufd_fault_fops_read()
  iommufd/selftest: Cover invalid read counts on vEVENTQ FD

 drivers/iommu/iommufd/eventq.c          | 29 ++++++++++++++++++++++---
 tools/testing/selftests/iommu/iommufd.c | 17 +++++++++++++++
 2 files changed, 43 insertions(+), 3 deletions(-)


base-commit: f25989c19028e8bf81e26e1133a99e3436c3afc2
-- 
2.43.0