Patch "dell-laptop: Fix allocating & freeing SMI buffer page" has been added to the 4.1-stable tree

Patch "dell-laptop: Fix allocating & freeing SMI buffer page" has been added to the 4.1-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    dell-laptop: Fix allocating & freeing SMI buffer page

to the 4.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dell-laptop-fix-allocating-freeing-smi-buffer-page.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From b8830a4e71b15d0364ac8e6c55301eea73f211da Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali.rohar@gmail.com>
Date: Tue, 23 Jun 2015 10:11:19 +0200
Subject: dell-laptop: Fix allocating & freeing SMI buffer page
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali.rohar@gmail.com>

commit b8830a4e71b15d0364ac8e6c55301eea73f211da upstream.

This commit fix kernel crash when probing for rfkill devices in dell-laptop
driver failed. Function free_page() was incorrectly used on struct page *
instead of virtual address of SMI buffer.

This commit also simplify allocating page for SMI buffer by using
__get_free_page() function instead of sequential call of functions
alloc_page() and page_address().

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/platform/x86/dell-laptop.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -305,7 +305,6 @@ static const struct dmi_system_id dell_q
 };
 
 static struct calling_interface_buffer *buffer;
-static struct page *bufferpage;
 static DEFINE_MUTEX(buffer_mutex);
 
 static int hwswitch_state;
@@ -1896,12 +1895,11 @@ static int __init dell_init(void)
 	 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
 	 * is passed to SMI handler.
 	 */
-	bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32);
-	if (!bufferpage) {
+	buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
+	if (!buffer) {
 		ret = -ENOMEM;
 		goto fail_buffer;
 	}
-	buffer = page_address(bufferpage);
 
 	ret = dell_setup_rfkill();
 
@@ -1965,7 +1963,7 @@ fail_backlight:
 	cancel_delayed_work_sync(&dell_rfkill_work);
 	dell_cleanup_rfkill();
 fail_rfkill:
-	free_page((unsigned long)bufferpage);
+	free_page((unsigned long)buffer);
 fail_buffer:
 	platform_device_del(platform_device);
 fail_platform_device2:


Patches currently in stable-queue which might be from pali.rohar@gmail.com are

queue-4.1/dell-laptop-fix-allocating-freeing-smi-buffer-page.patch