Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752917AbaBEP7N (ORCPT ); Wed, 5 Feb 2014 10:59:13 -0500 Received: from g6t0185.atlanta.hp.com ([15.193.32.62]:48901 "EHLO g6t0185.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752504AbaBEP7L (ORCPT ); Wed, 5 Feb 2014 10:59:11 -0500 Message-ID: <1391615569.5612.15.camel@misato.fc.hp.com> Subject: Re: [PATCH] ACPI hotplug: Fix panic on eject to ejected device From: Toshi Kani To: "Rafael J. Wysocki" Cc: "linux-acpi@vger.kernel.org" , "linux-kernel@vger.kernel.org" Date: Wed, 05 Feb 2014 08:52:49 -0700 In-Reply-To: <3540455.FvCglr7S6V@vostro.rjw.lan> References: <1391561308-18893-1-git-send-email-toshi.kani@hp.com> <3540455.FvCglr7S6V@vostro.rjw.lan> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.8.5 (3.8.5-2.fc19) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2014-02-05 at 11:05 +0000, Rafael J. Wysocki wrote: > On Tuesday, February 04, 2014 05:48:28 PM Toshi Kani wrote: > > When an eject request is sent to an ejected ACPI device, the following > > panic occurs: > > > > ACPI: \_SB_.SCK3.CPU3: ACPI_NOTIFY_EJECT_REQUEST event > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000070 > > IP: [] acpi_device_hotplug+0x10b/0x33b > > : > > Call Trace: > > [] acpi_hotplug_work_fn+0x1c/0x27 > > [] process_one_work+0x175/0x430 > > [] worker_thread+0x11b/0x3a0 > > > > This is becase device->handler is NULL in acpi_device_hotplug(). > > This case was used to fail in acpi_hotplug_notify_cb() as the target > > had no acpi_deivce. However, acpi_device now exists after ejection. > > > > Added a check to verify if acpi_device->handler is valid for an > > eject request in acpi_hotplug_notify_cb(). Note that handler passed > > from an argument is still valid while acpi_device->handler is NULL. > > > > Signed-off-by: Toshi Kani > > --- > > drivers/acpi/scan.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > > index 7384158..5cf6adf 100644 > > --- a/drivers/acpi/scan.c > > +++ b/drivers/acpi/scan.c > > @@ -484,7 +484,6 @@ static void acpi_device_hotplug(void *data, u32 src) > > static void acpi_hotplug_notify_cb(acpi_handle handle, u32 type, void *data) > > { > > u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; > > - struct acpi_scan_handler *handler = data; > > struct acpi_device *adev; > > acpi_status status; > > > > @@ -500,7 +499,9 @@ static void acpi_hotplug_notify_cb(acpi_handle handle, u32 type, void *data) > > break; > > case ACPI_NOTIFY_EJECT_REQUEST: > > acpi_handle_debug(handle, "ACPI_NOTIFY_EJECT_REQUEST event\n"); > > - if (!handler->hotplug.enabled) { > > + if (!adev->handler) > > + goto err_out; > > + if (!adev->handler->hotplug.enabled) { > > acpi_handle_err(handle, "Eject disabled\n"); > > ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED; > > goto err_out; > > OK, I'll queue this up for the next pull request, but it actually isn't safe, > because adev is not really guaranteed to exist here (it might have been deleted > already when this function is running). It should be safe since acpi_bus_get_device() fails in this function when adev does not exist. > The series of 24 patches I've sent recently addresses this problem, but they > are 3.15 material, so we need a stop-gap for 3.14. Great! Thanks, -Toshi -- 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/