After a variable is assigned the result of backlight_device_register, an error test should be performed before a dereference. A simplified version of the semantic match that finds this problem is as follows: (http://www.emn.fr/x-info/coccinelle/) // <smpl> @def0@ expression x; position p0; @@ x@p0 = backlight_device_register(...) @protected@ expression def0.x,E; position def0.p0; position p; statement S; @@ x@p0 ... when != x = E if (!IS_ERR(x) && ...) {<... x@p ...>} else S @unprotected@ expression def0.x,E; identifier fld; position def0.p0; position p != protected.p; @@ x@p0 ... when != x = E * x@p->fld // </smpl> Signed-off-by: Julien Brunel <brunel@xxxxxxx> Signed-off-by: Julia Lawall <julia@xxxxxxx> --- drivers/acpi/video.c | 2 ++ 1 file changed, 2 insertions(+) diff -u -p a/drivers/acpi/video.c b/drivers/acpi/video.c --- a/drivers/acpi/video.c +++ b/drivers/acpi/video.c @@ -752,6 +752,8 @@ static void acpi_video_device_find_cap(s sprintf(name, "acpi_video%d", count++); device->backlight = backlight_device_register(name, NULL, device, &acpi_backlight_ops); + if (IS_ERR(device->backlight)) + return; device->backlight->props.max_brightness = device->brightness->count-3; /* * If there exists the _BQC object, the _BQC object will be -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
