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

Pali Rohár
2015-06-21T08:41:31Z

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>
---
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

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