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SubjectRe: drivers/acpi/video.c: null pointer dereference
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On Thu, 2005-03-24 at 15:37, Adrian Bunk wrote:
> The Coverity checker found the following null pointer dereference in
> drivers/acpi/video.c:
>
> <-- snip -->
>
> ...
> static int
> acpi_video_switch_output(
> ...
> {
> ...
> struct acpi_video_device *dev=NULL;
> ...
> list_for_each_safe(node, next, &video->video_device_list) {
> struct acpi_video_device * dev = container_of(node,
> struct acpi_video_device, entry);
> ...
> }
> ...
> switch (event) {
> case ACPI_VIDEO_NOTIFY_CYCLE:
> case ACPI_VIDEO_NOTIFY_NEXT_OUTPUT:
> acpi_video_device_set_state(dev, 0);
> acpi_video_device_set_state(dev_next, 0x80000001);
> break;
> case ACPI_VIDEO_NOTIFY_PREV_OUTPUT:
> acpi_video_device_set_state(dev, 0);
> acpi_video_device_set_state(dev_prev, 0x80000001);
> ...
>
> <-- snip -->
>
>
> Two different variables of the same name within 40 lines of code are a
> good indication that something's wrong...
>
>
> The outer "dev" variable is never assigned any value different from
> NULL.
>
> acpi_video_device_set_state dereferences this variable.
>
>
> cu
> Adrian

Looks like we should do this:


===== drivers/acpi/video.c 1.8 vs edited =====
--- 1.8/drivers/acpi/video.c 2005-01-06 02:06:20 -05:00
+++ edited/drivers/acpi/video.c 2005-03-24 15:44:33 -05:00
@@ -1585,7 +1585,7 @@
ACPI_FUNCTION_TRACE("acpi_video_switch_output");

list_for_each_safe(node, next, &video->video_device_list) {
- struct acpi_video_device * dev = container_of(node, struct acpi_video_device, entry);
+ dev = container_of(node, struct acpi_video_device, entry);
status = acpi_video_device_get_state(dev, &state);
if (state & 0x2){
dev_next = container_of(node->next, struct acpi_video_device, entry);
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