Always perform bounds-checking in metaslab_free_concrete

[asomers]

The vd->vdev_ms access can overflow due to on-disk corruption, not just due to programming bugs. So it makes sense to check its boundaries even in production builds.

Sponsored by: ConnectWise
Signed-off-by: Alan Somers [email protected]

Motivation and Context

Prevents an out-of-bounds memory access due to on-disk corruption. The out of bounds access usually results in a page fault, but its effects are unpredictable. Better to cleanly panic instead. The original corruption was probably caused by the same underlying cause as #16626, combined with inadequate sanity checking of the block pointers.

Description

Changes in existing ASSERT into a VERIFY

How Has This Been Tested?

Ran the ZFS test suite on FreeBSD

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[amotin]

I have no objections, but wonder if this is the earliest place we can catch the corruption.

[amotin]

This slightly echoes with #17094.

[asomers]

I have no objections, but wonder if this is the earliest place we can catch the corruption.

I hope there's a better place to catch it. I plan to keep working on the problem. But in the meantime I think this change is correct. Maybe after #17094 there will be a better way to handle it.