Re: [PATCH v8 2/2] block: add overflow checks for Amiga partition support

[Michael Schmitz <schmitzmic@gmail.com>]

Hi Geert,

On 11/08/22 23:40, Geert Uytterhoeven wrote:
> Hi Christoph,
>
> On Tue, Jul 26, 2022 at 1:43 PM Christoph Hellwig <hch@infradead.org> wrote:
>> On Tue, Jul 26, 2022 at 04:57:47PM +1200, Michael Schmitz wrote:
>>> The Amiga partition parser module uses signed int for partition sector
>>> address and count, which will overflow for disks larger than 1 TB.
>>>
>>> Use u64 as type for sector address and size to allow using disks up to
>>> 2 TB without LBD support, and disks larger than 2 TB with LBD. The RBD
>>> format allows to specify disk sizes up to 2^128 bytes (though native
>>> OS limitations reduce this somewhat, to max 2^68 bytes), so check for
>>> u64 overflow carefully to protect against overflowing sector_t.
>>>
>>> Bail out if sector addresses overflow 32 bits on kernels without LBD
>>> support.
>>>
>>> This bug was reported originally in 2012, and the fix was created by
>>> the RDB author, Joanne Dow <jdow@earthlink.net>. A patch had been
>>> discussed and reviewed on linux-m68k at that time but never officially
>>> submitted (now resubmitted as separate patch).
>>> This patch adds additional error checking and warning messages.
>>>
>>> Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=43511
>>> Reported-by: Martin Steigerwald <Martin@lichtvoll.de>
>>> Message-ID: <201206192146.09327.Martin@lichtvoll.de>
>>> Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
>>> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
>>> --- a/block/partitions/amiga.c
>>> +++ b/block/partitions/amiga.c
>>>                if (!data) {
>>> -                     pr_err("Dev %s: unable to read RDB block %d\n",
>>> -                            state->disk->disk_name, blk);
>>> +                     pr_err("Dev %s: unable to read RDB block %llu\n",
>>> +                            state->disk->disk_name, (u64) blk);
>> No need for the various printk casts, a sector_t is always an
>> unsigned long long.
> That is true, as of commit 72deb455b5ec619f
> ("block: remove CONFIG_LBDAF") in v5.2.
> Since 4.9, 4.14, and 4.19 are still receiving stable updates, the
> cast should be re-added when this is backported.

Does this require a note in the commit message, or explicit CC to Greg?

Cheers,

     Michael

> Gr{oetje,eeting}s,
>
>                          Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                  -- Linus Torvalds