From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:48849)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <armbru@redhat.com>) id 1avPeo-0006Oi-5T
	for qemu-devel@nongnu.org; Wed, 27 Apr 2016 09:37:39 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <armbru@redhat.com>) id 1avPei-0005YK-IS
	for qemu-devel@nongnu.org; Wed, 27 Apr 2016 09:37:34 -0400
From: Markus Armbruster <armbru@redhat.com>
References: <1455546821-6671-1-git-send-email-berrange@redhat.com>
	<1455546821-6671-2-git-send-email-berrange@redhat.com>
	<8737q7ierk.fsf@dusky.pond.sub.org>
Date: Wed, 27 Apr 2016 15:37:21 +0200
In-Reply-To: <8737q7ierk.fsf@dusky.pond.sub.org> (Markus Armbruster's message
	of "Wed, 27 Apr 2016 11:26:23 +0200")
Message-ID: <87k2jjfa0e.fsf@dusky.pond.sub.org>
MIME-Version: 1.0
Content-Type: text/plain
Subject: Re: [Qemu-devel] [PATCH v6 01/10] qom: add helpers for
 UserCreatable object types
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: "Daniel P. Berrange" <berrange@redhat.com>
Cc: qemu-devel@nongnu.org, Kevin Wolf <kwolf@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, qemu-block@nongnu.org, Eric Blake <eblake@redhat.com>

Markus Armbruster <armbru@redhat.com> writes:

> This commit regresses error message quality from
>
>     $ qemu-system-x86_64 -nodefaults -display none -object secret,id=sec0,data=letmein,format=raw,foo=bar
>     qemu-system-x86_64: -object secret,id=sec0,data=letmein,format=raw,foo=bar: Property '.foo' not found
>
> to just
>
>     qemu-system-x86_64: Property '.foo' not found
>
> Clue: cur_loc points to garbage.
>
>     (gdb) p cur_loc
>     $1 = (Location *) 0x7fffffffdc10
>     (gdb) p *cur_loc
>     $2 = {kind = (unknown: 4294958128), num = 32767, 
>       ptr = 0x555555b804a2 <error_report_err+44>, prev = 0x5555565d2770 <std_loc>}
>
> Looks like cur_loc is dangling.  Happens when you forget to loc_pop() a
> Location before it dies.  This one is on the stack.
>
> *Might* be release critical.
>
> For comparison, this is how it looks before the patch:
>
>     (gdb) p cur_loc
>     $1 = (Location *) 0x7fffffffdc10
>     (gdb) p *cur_loc
>     $2 = {kind = LOC_CMDLINE, num = 2, ptr = 0x7fffffffe018, prev = 
>         0x5555565d2770 <std_loc>}
>
> Reported-by: Eric Blake <eblake@redhat.com>

I think I nailed it.  Preparing patches...