Re: [PATCH] btrfs-progs: print-tree: do sanity checks for dir items

[Josef Bacik <josef@toxicpanda.com>]

On Tue, Jun 04, 2024 at 02:19:08PM +0930, Qu Wenruo wrote:
> There is a bug report that with UBSAN enabled, fuzz/006 test case would
> crash.
> 
> It turns out that the image bko-154021-invalid-drop-level.raw has
> invalid dir items, that the name/data len is beyond the item.
> 
> And if we try to read beyond the eb boundary, UBSAN got triggered.
> 
> Normally in kernel tree-checker would reject such metadata in the first
> place, but in btrfs-progs we can not go that strict or we can not do a
> lot of repair.
> 
> So here just enhance print_dir_item() to do extra sanity checks for
> data/name len before reading the contents.
> 
> Issue: #805
> Signed-off-by: Qu Wenruo <wqu@suse.com>

I'd rather not duplicate this check.

Is the print-tree coming from repair?  If that's the case then I'd manually call
check_leaf to make sure the pointers are all correct before calling print tree,
otherwise if it's from a different tool we need to make sure the strict checking
is happening for that tool, we should only be bypassing the strict checking for
repair.  Thanks,

Josef