linux-kernel - Re: [EXTERNAL] Re: [PATCH] padata: Fix possible divide-by-0 panic in padata_mt

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87bk1mnvn9.fsf@kamlesh.i-did-not-set--mail-host-address--so-tickle-me>
Date: Wed, 21 Aug 2024 13:40:50 +0530
From: Kamlesh Gurudasani <kamlesh@...com>
To: Daniel Jordan <daniel.m.jordan@...cle.com>,
        Herbert Xu
	<herbert@...dor.apana.org.au>
CC: Waiman Long <longman@...hat.com>, <steffen.klassert@...unet.com>,
        <akpm@...ux-foundation.org>, <linux-crypto@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [EXTERNAL] Re: [PATCH] padata: Fix possible divide-by-0 panic
 in padata_mt_helper()

Daniel Jordan <daniel.m.jordan@...cle.com> writes:

> On Tue, Aug 20, 2024 at 12:06:47PM GMT, Herbert Xu wrote:
>> On Mon, Aug 19, 2024 at 06:29:52PM -0400, Daniel Jordan wrote:
>> >
>> > The DIV_ROUND_UP approach reads a bit nicer to me, but I can imagine
>> > oddball cases where rounding up is undesirable (say, near-zero values
>> > for size, min_chunk, and align; padata_work_alloc_mt returns many fewer
>> > works than requested; and a single unit of work is very expensive) so
>> > that rounding up makes a bigger difference.  So, the way it now is seems
>> > ok.
>> 
>> In that case let's do the max ahead of the align check:
>> 
>> 	ps.chunk_size = max(ps.chunk_size, 1ul);
>> 	ps.chunk_size = roundup(ps.chunk_size, job->align);
>> 
>> If we do it after then it may come out unaligned (e.g., job->align = 8
>> and ps.chunk_size = 1).
>
> Sure, I think Kamlesh was the first to suggest max, so maybe Kamlesh
> would like to make the change.  I'll send a patch otherwise.
Thanks for consideration, Daniel. I'll send a patch.

cheers,
Kamlesh