Re: [PATCH v2] btrfs: reject empty non-root tree blocks at read time

[Qu Wenruo]

在 2026/4/9 18:39, Qu Wenruo 写道:
> 在 2026/4/9 17:41, ZhengYuan Huang 写道:
> > [CAUSE]
> > The old btrfs_verify_level_key() path rejected tree blocks with
> > nritems == 0 whenever the parent check provided a first key.
> > Commit 947a629988f1 ("btrfs: move tree block parentness check into
> > validate_extent_buffer()") moved the parentness checks into the read-time
> > validation path, but it dropped that guard. This lets an empty non-root
> > tree block pass read-time validation even though slot 0 must exist if the
> > parent provides a first key.
>
> Wait for a second, there is still the nritems == 0 check inside 
> btrfs_verify_level_key().
>
> It looks like there is a missing link.
>
> Is the btrfs_buffer_uptodate() call inside read_block_for_search() not 
> passing the correct check structure?

And if you can provide the fuzzed image for each of your fix/report, it 
will help a lot.

It will not only provide a reliable way to test, but also allows 
reviewer to verify if the root cause is correct.

> Thanks,
> Qu