From: Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
To: "Luck, Tony" <tony.luck-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: Insu Yun <wuninsu-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
"linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"taesoo-/4noJB3qBVQ3uPMLIKxrzw@public.gmane.org"
<taesoo-/4noJB3qBVQ3uPMLIKxrzw@public.gmane.org>,
"yeongjin.jang-/4noJB3qBVQ3uPMLIKxrzw@public.gmane.org"
<yeongjin.jang-/4noJB3qBVQ3uPMLIKxrzw@public.gmane.org>,
"insu-/4noJB3qBVQ3uPMLIKxrzw@public.gmane.org"
<insu-/4noJB3qBVQ3uPMLIKxrzw@public.gmane.org>,
"changwoo-/4noJB3qBVQ3uPMLIKxrzw@public.gmane.org"
<changwoo-/4noJB3qBVQ3uPMLIKxrzw@public.gmane.org>
Subject: Re: [PATCH] efi: fix out-of-bounds null overwrite vulnerability
Date: Mon, 11 Jan 2016 14:16:05 +0000 [thread overview]
Message-ID: <20160111141605.GC2644@codeblueprint.co.uk> (raw)
In-Reply-To: <3908561D78D1C84285E8C5FCA982C28F39FA7208-8oqHQFITsIE64kNsxIetb7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
On Fri, 08 Jan, at 04:47:17PM, Luck, Tony wrote:
> > But this function doesn't use snprintf(), it uses scnprintf() which
> > returns the number of characters written into buf and, because
> > scnprintf() largely follows vnsprintf(), it will never write more than
> > 'size' bytes into the buffer.
>
> if (bank && device)
> n = snprintf(msg, len, "DIMM location: %s %s ", bank, device);
>
> That looks like "snprintf", not "scnprintf" to me :-)
Oops! Can you believe I looked at the wrong function?
> What about using:
>
> msg[len] = '\0';
>
> to guarantee NUL termination?
But that may leave garbage bytes in 'rcd_decode_str' in the case where
the string isn't as long as 'len'.
How about memset()'ing the buffer to zero and deleting the NUL
termination line?
WARNING: multiple messages have this Message-ID (diff)
From: Matt Fleming <matt@codeblueprint.co.uk>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Insu Yun <wuninsu@gmail.com>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"taesoo@gatech.edu" <taesoo@gatech.edu>,
"yeongjin.jang@gatech.edu" <yeongjin.jang@gatech.edu>,
"insu@gatech.edu" <insu@gatech.edu>,
"changwoo@gatech.edu" <changwoo@gatech.edu>
Subject: Re: [PATCH] efi: fix out-of-bounds null overwrite vulnerability
Date: Mon, 11 Jan 2016 14:16:05 +0000 [thread overview]
Message-ID: <20160111141605.GC2644@codeblueprint.co.uk> (raw)
In-Reply-To: <3908561D78D1C84285E8C5FCA982C28F39FA7208@ORSMSX114.amr.corp.intel.com>
On Fri, 08 Jan, at 04:47:17PM, Luck, Tony wrote:
> > But this function doesn't use snprintf(), it uses scnprintf() which
> > returns the number of characters written into buf and, because
> > scnprintf() largely follows vnsprintf(), it will never write more than
> > 'size' bytes into the buffer.
>
> if (bank && device)
> n = snprintf(msg, len, "DIMM location: %s %s ", bank, device);
>
> That looks like "snprintf", not "scnprintf" to me :-)
Oops! Can you believe I looked at the wrong function?
> What about using:
>
> msg[len] = '\0';
>
> to guarantee NUL termination?
But that may leave garbage bytes in 'rcd_decode_str' in the case where
the string isn't as long as 'len'.
How about memset()'ing the buffer to zero and deleting the NUL
termination line?
next prev parent reply other threads:[~2016-01-11 14:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-07 19:05 [PATCH] efi: fix out-of-bounds null overwrite vulnerability Insu Yun
2016-01-07 19:05 ` Insu Yun
[not found] ` <1452193530-76672-1-git-send-email-wuninsu-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-01-08 10:13 ` Matt Fleming
2016-01-08 10:13 ` Matt Fleming
[not found] ` <20160108101323.GA2532-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2016-01-08 16:47 ` Luck, Tony
2016-01-08 16:47 ` Luck, Tony
[not found] ` <3908561D78D1C84285E8C5FCA982C28F39FA7208-8oqHQFITsIE64kNsxIetb7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
2016-01-11 14:16 ` Matt Fleming [this message]
2016-01-11 14:16 ` Matt Fleming
[not found] ` <20160111141605.GC2644-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2016-01-11 18:16 ` Luck, Tony
2016-01-11 18:16 ` Luck, Tony
2016-01-14 11:12 ` Matt Fleming
[not found] ` <20160114111200.GA2810-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2016-01-15 2:06 ` Tony Luck
2016-01-15 2:06 ` Tony Luck
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