Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757934Ab3GLXnb (ORCPT ); Fri, 12 Jul 2013 19:43:31 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:40499 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753289Ab3GLXn3 (ORCPT ); Fri, 12 Jul 2013 19:43:29 -0400 From: "Rafael J. Wysocki" To: Toshi Kani Cc: Yasuaki Ishimatsu , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ACPI / memhotplug: Fix a stale pointer in error path Date: Sat, 13 Jul 2013 01:53:18 +0200 Message-ID: <1628443.pD3ROIrBQn@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.10.0+; KDE/4.9.5; x86_64; ; ) In-Reply-To: <1373668116.24916.43.camel@misato.fc.hp.com> References: <1373474833-14047-1-git-send-email-toshi.kani@hp.com> <1907509.WiI0tI5uDZ@vostro.rjw.lan> <1373668116.24916.43.camel@misato.fc.hp.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4091 Lines: 104 On Friday, July 12, 2013 04:28:36 PM Toshi Kani wrote: > On Fri, 2013-07-12 at 23:40 +0200, Rafael J. Wysocki wrote: > > On Friday, July 12, 2013 03:12:24 PM Toshi Kani wrote: > > > On Fri, 2013-07-12 at 23:13 +0200, Rafael J. Wysocki wrote: > > > > On Friday, July 12, 2013 03:01:15 PM Toshi Kani wrote: > > > > > On Fri, 2013-07-12 at 22:42 +0200, Rafael J. Wysocki wrote: > > > > > > On Friday, July 12, 2013 08:51:29 AM Toshi Kani wrote: > > > > > > > On Fri, 2013-07-12 at 09:24 +0900, Yasuaki Ishimatsu wrote: > > > > > > > > (2013/07/11 1:47), Toshi Kani wrote: > > > > > > > > > device->driver_data needs to be cleared when releasing its data, > > > > > > > > > mem_device, in an error path of acpi_memory_device_add(). > > > > > > > > > > > > > > > > > > Signed-off-by: Toshi Kani > > > > > > > > > --- > > > > > > > > > > > > > > > > Reviewed-by: Yasuaki Ishimatsu > > > > > > > > > > > > > > Thanks Yasuaki! > > > > > > > > > > > > Queued up as a fix for 3.11. > > > > > > > > > > Thanks! > > > > > > > > > > > Do we need that in -stable as well? > > > > > > > > > > Good point. Yes, we need that in -stable as well. > > > > > > > > What's the oldest mainline major release that fix is applicable to? > > > > > > The fix is applicable all ways up to 2.6.32. > > > > For -stable I'll need to say some more about what practical consequences of > > the bug are. Is it difficult to trigger? > > The function evaluates _CRS of memory device objects, and fails when it > gets an unexpected resource or cannot allocate a memory. OK, so this is essentially about surviving unexpected external input, which I suppose is serious enough. > A kernel crash > or data corruption may occur when the kernel accessed a stale pointer. > That said, I am not sure how critical this issue is for old kernels > since I do not think there are many platforms that support memory > hotplug today. Which doesn't matter. People may want to run 3.10.y on future hardware too. > After reading the recent -stable discussion on LKML, now > I am not sure if this fix should be applied for -stable. Well, I don't necessarily agree with some things being said there. I guess I'll need to say something in that thread. :-) > I instrumented the kernel to generate an error for testing this change. OK Thanks, Rafael > > > > > > > > > drivers/acpi/acpi_memhotplug.c | 1 + > > > > > > > > > 1 file changed, 1 insertion(+) > > > > > > > > > > > > > > > > > > diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c > > > > > > > > > index c711d11..999adb5 100644 > > > > > > > > > --- a/drivers/acpi/acpi_memhotplug.c > > > > > > > > > +++ b/drivers/acpi/acpi_memhotplug.c > > > > > > > > > @@ -323,6 +323,7 @@ static int acpi_memory_device_add(struct acpi_device *device, > > > > > > > > > /* Get the range from the _CRS */ > > > > > > > > > result = acpi_memory_get_device_resources(mem_device); > > > > > > > > > if (result) { > > > > > > > > > + device->driver_data = NULL; > > > > > > > > > kfree(mem_device); > > > > > > > > > return result; > > > > > > > > > } > > > > > > > > > -- > > > > > > > > > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > > > > > > > > > the body of a message to majordomo@vger.kernel.org > > > > > > > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/