acpi ->video_device_list corruption

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.

Included as a MIME attachment is a compressed dmesg from an affected system. The patch was seen to resolve the issue on the affected system.

vs. 2.6.24-rc5

Signed-off-by William Irwin <[email protected]>

-- wli

drivers/acpi/video.c +0 -0

index 44a0d9b..7895d57 100644

IMO the memset(ptr, 0, sizeof(*ptr)) idiom is both safer and avoids having to write an uninteresting type name.

Quoted 2 lines · Mikael Pettersson

IMO the memset(ptr, 0, sizeof(*ptr)) idiom is both safer and avoids having to write an uninteresting type name.

How about this, then?

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 <[email protected]>

drivers/acpi/video.c +2 -3

index 44a0d9b..bd77e81 100644
@@ -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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Acked-by Mikael Pettersson <[email protected]>