Re: [PATCH 3/4] dell-laptop: Fix allocating & freeing SMI buffer page

Darren Hart
2015-06-22T19:04:07Z

On Sun, Jun 21, 2015 at 10:41:03AM +0200, Pali Rohár wrote:
> 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>

Looks good - please resend with Cc to stable - that's the simplest path to
inclusion in stable.

> ---
> drivers/platform/x86/dell-laptop.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index aaef335..0a91599 100644
> --- a/drivers/platform/x86/dell-laptop.c
> +++ b/drivers/platform/x86/dell-laptop.c
> @@ -306,7 +306,6 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
> };
>
> static struct calling_interface_buffer *buffer;
> -static struct page *bufferpage;
> static DEFINE_MUTEX(buffer_mutex);
>
> static int hwswitch_state;
> @@ -2097,12 +2096,11 @@ 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();
>
> @@ -2165,7 +2163,7 @@ static int __init dell_init(void)
> fail_backlight:
> 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:
> --
> 1.7.9.5
>
>

--
Darren Hart
Intel Open Source Technology Center
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