[PATCH 5.15 286/846] backlight: qcom-wled: Validate enabled string indices in DT

[Greg Kroah-Hartman]

From: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>

[ Upstream commit c05b21ebc5bce3ecc78c2c71afd76d92c790a2ac ]

The strings passed in DT may possibly cause out-of-bounds register
accesses and should be validated before use.

Fixes: 775d2ffb4af6 ("backlight: qcom-wled: Restructure the driver for WLED3")
Signed-off-by: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxxx>
Reviewed-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211115203459.1634079-2-marijn.suijten@xxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/video/backlight/qcom-wled.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index d094299c2a485..8a42ed89c59c9 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -1528,12 +1528,28 @@ static int wled_configure(struct wled *wled)
 	string_len = of_property_count_elems_of_size(dev->of_node,
 						     "qcom,enabled-strings",
 						     sizeof(u32));
-	if (string_len > 0)
+	if (string_len > 0) {
+		if (string_len > wled->max_string_count) {
+			dev_err(dev, "Cannot have more than %d strings\n",
+				wled->max_string_count);
+			return -EINVAL;
+		}
+
 		of_property_read_u32_array(dev->of_node,
 						"qcom,enabled-strings",
 						wled->cfg.enabled_strings,
 						sizeof(u32));
 
+		for (i = 0; i < string_len; ++i) {
+			if (wled->cfg.enabled_strings[i] >= wled->max_string_count) {
+				dev_err(dev,
+					"qcom,enabled-strings index %d at %d is out of bounds\n",
+					wled->cfg.enabled_strings[i], i);
+				return -EINVAL;
+			}
+		}
+	}
+
 	return 0;
 }
 
-- 
2.34.1