acpi ->video_device_list corruption

William Lee Irwin III
2007-12-12T10:15:05Z

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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 <wli@holomorphy.com>

-- wli

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 44a0d9b..7895d57 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(struct acpi_video_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(struct acpi_video_bus_cap));
if (ACPI_SUCCESS(acpi_get_handle(video->device->handle, "_DOS", &h_dummy1))) {
video->cap._DOS = 1;
}

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