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From: Eric Biggers <ebiggers3@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>,
	keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com, Tycho Andersen <tycho@tycho.ws>,
	Kees Cook <keescook@chromium.org>,
	Stephan Mueller <smueller@chronox.de>,
	Eric Biggers <ebiggers@google.com>
Subject: Re: [PATCH] dh key: fix rounding up KDF output length
Date: Mon, 25 Jun 2018 10:14:26 -0700	[thread overview]
Message-ID: <20180625171426.GA180889@gmail.com> (raw)
In-Reply-To: <17595.1528472278@warthog.procyon.org.uk>

Hi David,

On Fri, Jun 08, 2018 at 04:37:58PM +0100, David Howells wrote:
> Eric Biggers <ebiggers3@gmail.com> wrote:
> 
> > Commit 383203eff718 ("dh key: get rid of stack allocated array") changed
> > kdf_ctr() to assume that the length of key material to derive is a
> > multiple of the digest size.  The length was supposed to be rounded up
> > accordingly.  However, the round_up() macro was used which only gives
> > the correct result on power-of-2 arguments, whereas not all hash
> > algorithms have power-of-2 digest sizes.  In some cases this resulted in
> > a write past the end of the 'outbuf' buffer.
> > 
> > Fix it by switching to roundup(), which works for non-power-of-2 inputs.
> 
> Applied.

Applied to where?  When are you planning to send this to Linus?  Note that this
was a regression from v4.17 to v4.18-rc1.

Thanks,

- Eric

      reply	other threads:[~2018-06-25 17:14 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-07 13:07 KASAN: slab-out-of-bounds Write in sha1_finup syzbot
2018-06-07 14:43 ` syzbot
2018-06-07 19:12 ` [PATCH] dh key: fix rounding up KDF output length Eric Biggers
2018-06-07 19:16   ` Kees Cook
2018-06-07 19:28     ` James Morris
2018-06-07 19:28     ` Eric Biggers
2018-06-07 20:28   ` Tycho Andersen
2018-06-08 15:37 ` David Howells
2018-06-25 17:14   ` Eric Biggers [this message]

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