Re: [PATCH v7 2/2] block: add overflow checks for Amiga partition support

Finn Thain
2023-06-14T00:06:37Z

On Wed, 14 Jun 2023, Michael Schmitz wrote:

> My last version (v9) still applies, but that one still threw a sparse
> warning for patch 2:
>
> Link:https://lore.kernel.org/all/202208231319.Ng5RTzzg-lkp@intel.com
>
> Not sure how to treat that one - rdb_CylBlocks is not declared as big
> endian so the warning is correct, but as far as I can see, for all
> practical purposes rdb_CylBlocks would be expected to be in big endian
> order (partition usually prepared on a big endian system)?
>
> I can drop the be32_to_cpu conversion (and would expect to see a warning
> printed on little endian systems), or force the cast to __be32. Or
> rather drop that consistency check outright...
>

The new warning comes from this new code:

if (cylblk > be32_to_cpu((__be32)rdb->rdb_CylBlocks)) {
pr_warn("Dev %s: cylblk %u > rdb_CylBlocks %u!\n",
state->disk->disk_name, cylblk,
be32_to_cpu(rdb->rdb_CylBlocks));
}

The __be32 cast appears in the first line but not the fourth, which is an
inconsistency you might want to tidy up. However, both lines produce the
same sparse warning here.

The inconsistent use of big-endian and native-endian members in struct
RigidDiskBlock looks like the root cause to me but I know nothing about
Amiga partition maps so I'm not going to guess.