[PATCH 5/6] backlight: qcom-wled: Check for auto-detection callback in wled_ovp_irq_handler()

[Lee Jones <lee@kernel.org>]

The wled_auto_detection_required callback is only populated for WLED4
and WLED5 hardware, remaining NULL on WLED3 (where automatic string
detection is not supported).

However, wled_configure_ovp_irq() still registers wled_ovp_irq_handler()
on WLED3 when an "ovp" interrupt is present in the Device Tree.  If an
OVP fault interrupt fires on WLED3, wled_ovp_irq_handler()
unconditionally invokes wled->wled_auto_detection_required(), causing a
NULL pointer dereference.

Verify that wled->wled_auto_detection_required is non-NULL before
invoking it in wled_ovp_irq_handler().

Fixes: f16899a6a7d4 ("backlight: qcom-wled: Add callback functions")
Closes: https://sashiko.dev/#/bug/linux-d3eba287-2af9-43fb-851f-78ab3df0f35b
Cc: stable@vger.kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>
---
Cc: David Heidelberg <david@ixit.cz>
Cc: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

 drivers/video/backlight/qcom-wled.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index 8d4d7fe5e84d..06300d403f8f 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -917,7 +917,8 @@ static irqreturn_t wled_ovp_irq_handler(int irq, void *_wled)
 			int_sts, fault_sts);
 
 	if (fault_sts & WLED3_CTRL_REG_OVP_FAULT_BIT) {
-		if (wled->wled_auto_detection_required(wled)) {
+		if (wled->wled_auto_detection_required &&
+		    wled->wled_auto_detection_required(wled)) {
 			mutex_lock(&wled->lock);
 			wled_auto_string_detection(wled);
 			mutex_unlock(&wled->lock);
-- 
2.56.0.385.gac671c819a-goog