Re: [PATCH v3 RESEND] hfs: validate catalog CNIDs before instantiating inodes

[Viacheslav Dubeyko]

On Tue, 2026-07-07 at 18:31 -0300, dave mad maxXx wrote:
> Hi Slava,
> Thank you for the review.
> Yes, I agree that the initial length validation can be simplified to:
> rec_len = fd->entrylength;
> if (rec_len <= 0 || rec_len > sizeof(rec))
>         return -EIO;
> 
> I also agree that, for the fixed-size file and directory catalog
> records, the checks should require the exact record size:
> rec_len != sizeof(struct hfs_cat_file)
> 
> and:
> rec_len != sizeof(struct hfs_cat_dir)
> 
> Regarding hfs_write_inode(), I intentionally left it unchanged
> because the patch was trying to reject invalid CNIDs at the catalog
> lookup and inode-instantiation boundaries, before a corrupted inode
> could reach writeback.
> However, I agree that an additional validation there may be useful as
> defense in depth. Would you prefer hfs_is_valid_cnid() to be checked
> in hfs_write_inode() as well, and should that check precede the
> existing BUG path while otherwise leaving its behavior unchanged?
> I will prepare the next revision after your guidance on that point.

Let's leave hfs_write_inode() untouched. I don't see a valid point in
this modification.

Thanks,
Slava.