From: Tycho Andersen <tycho@tycho.ws>
To: Eric Biggers <ebiggers3@gmail.com>
Cc: David Howells <dhowells@redhat.com>,
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,
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: Thu, 07 Jun 2018 20:28:31 +0000 [thread overview]
Message-ID: <20180607202831.GG9999@cisco> (raw)
In-Reply-To: <20180607191201.97080-1-ebiggers3@gmail.com>
On Thu, Jun 07, 2018 at 12:12:01PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> 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.
>
> Reported-by: syzbot+486f97f892efeb2075a3@syzkaller.appspotmail.com
> Reported-by: syzbot+29d17b7898b41ee120a5@syzkaller.appspotmail.com
> Reported-by: syzbot+8a608baf8751184ec727@syzkaller.appspotmail.com
> Reported-by: syzbot+d04e58bd384f1fe0b112@syzkaller.appspotmail.com
> Fixes: 383203eff718 ("dh key: get rid of stack allocated array")
> Signed-off-by: Eric Biggers <ebiggers@google.com>
Arg, thanks.
Acked-by: Tycho Andersen <tycho@tycho.ws>
WARNING: multiple messages have this Message-ID (diff)
From: Tycho Andersen <tycho@tycho.ws>
To: Eric Biggers <ebiggers3@gmail.com>
Cc: David Howells <dhowells@redhat.com>,
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,
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: Thu, 7 Jun 2018 14:28:31 -0600 [thread overview]
Message-ID: <20180607202831.GG9999@cisco> (raw)
In-Reply-To: <20180607191201.97080-1-ebiggers3@gmail.com>
On Thu, Jun 07, 2018 at 12:12:01PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> 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.
>
> Reported-by: syzbot+486f97f892efeb2075a3@syzkaller.appspotmail.com
> Reported-by: syzbot+29d17b7898b41ee120a5@syzkaller.appspotmail.com
> Reported-by: syzbot+8a608baf8751184ec727@syzkaller.appspotmail.com
> Reported-by: syzbot+d04e58bd384f1fe0b112@syzkaller.appspotmail.com
> Fixes: 383203eff718 ("dh key: get rid of stack allocated array")
> Signed-off-by: Eric Biggers <ebiggers@google.com>
Arg, thanks.
Acked-by: Tycho Andersen <tycho@tycho.ws>
WARNING: multiple messages have this Message-ID (diff)
From: tycho@tycho.ws (Tycho Andersen)
To: linux-security-module@vger.kernel.org
Subject: [PATCH] dh key: fix rounding up KDF output length
Date: Thu, 7 Jun 2018 14:28:31 -0600 [thread overview]
Message-ID: <20180607202831.GG9999@cisco> (raw)
In-Reply-To: <20180607191201.97080-1-ebiggers3@gmail.com>
On Thu, Jun 07, 2018 at 12:12:01PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> 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.
>
> Reported-by: syzbot+486f97f892efeb2075a3 at syzkaller.appspotmail.com
> Reported-by: syzbot+29d17b7898b41ee120a5 at syzkaller.appspotmail.com
> Reported-by: syzbot+8a608baf8751184ec727 at syzkaller.appspotmail.com
> Reported-by: syzbot+d04e58bd384f1fe0b112 at syzkaller.appspotmail.com
> Fixes: 383203eff718 ("dh key: get rid of stack allocated array")
> Signed-off-by: Eric Biggers <ebiggers@google.com>
Arg, thanks.
Acked-by: Tycho Andersen <tycho@tycho.ws>
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next prev parent reply other threads:[~2018-06-07 20:28 UTC|newest]
Thread overview: 23+ 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 19:12 ` Eric Biggers
2018-06-07 19:12 ` Eric Biggers
2018-06-07 19:16 ` Kees Cook
2018-06-07 19:16 ` Kees Cook
2018-06-07 19:16 ` Kees Cook
2018-06-07 19:28 ` James Morris
2018-06-07 19:28 ` James Morris
2018-06-07 19:28 ` James Morris
2018-06-07 19:28 ` Eric Biggers
2018-06-07 19:28 ` Eric Biggers
2018-06-07 19:28 ` Eric Biggers
2018-06-07 20:28 ` Tycho Andersen [this message]
2018-06-07 20:28 ` Tycho Andersen
2018-06-07 20:28 ` Tycho Andersen
2018-06-08 15:37 ` David Howells
2018-06-08 15:37 ` David Howells
2018-06-08 15:37 ` David Howells
2018-06-25 17:14 ` Eric Biggers
2018-06-25 17:14 ` Eric Biggers
2018-06-25 17:14 ` Eric Biggers
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