Re: acpi ->video_device_list corruption

[Mikael Pettersson <mikpe@it.uu.se>]

William Lee Irwin III writes:
 > On Wed, Dec 12, 2007 at 12:48:09PM +0100, Mikael Pettersson wrote:
 > > IMO the memset(ptr, 0, sizeof(*ptr)) idiom is both safer
 > > and avoids having to write an uninteresting type name.
 > 
 > How about this, then?

Looks good.

Acked-by: Mikael Pettersson <mikpe@it.uu.se>

 > 
 > The ->cap fields of struct acpi_video_device and struct acpi_video_bus
 > are 1B each, not 4B. The oversized memset()'s corrupted the subsequent
 > list_head fields. This resulted in silent corruption without
 > CONFIG_DEBUG_LIST and BUG's with it. This patch uses sizeof() to pass
 > the proper bounds to the memset() calls and thereby correct the bugs.
 > 
 > The patch was seen to resolve the issue on the affected system.
 > 
 > vs. 2.6.24-rc5
 > 
 > Signed-off-by: William Irwin <wli@holomorphy.com>
 > 
 > diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
 > index 44a0d9b..bd77e81 100644
 > --- a/drivers/acpi/video.c
 > +++ b/drivers/acpi/video.c
 > @@ -577,7 +577,7 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
 >  	struct acpi_video_device_brightness *br = NULL;
 >  
 >  
 > -	memset(&device->cap, 0, 4);
 > +	memset(&device->cap, 0, sizeof(device->cap));
 >  
 >  	if (ACPI_SUCCESS(acpi_get_handle(device->dev->handle, "_ADR", &h_dummy1))) {
 >  		device->cap._ADR = 1;
 > @@ -697,7 +697,7 @@ static void acpi_video_bus_find_cap(struct acpi_video_bus *video)
 >  {
 >  	acpi_handle h_dummy1;
 >  
 > -	memset(&video->cap, 0, 4);
 > +	memset(&video->cap, 0, sizeof(video->cap));
 >  	if (ACPI_SUCCESS(acpi_get_handle(video->device->handle, "_DOS", &h_dummy1))) {
 >  		video->cap._DOS = 1;
 >  	}
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