[PATCH 04/10] backlight: qcom-wled: Validate enabled string indices in DT

[Marijn Suijten]

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.suij...@somainline.org>
Reviewed-by: AngeloGioacchino Del Regno 
<angelogioacchino.delre...@somainline.org>
---
 drivers/video/backlight/qcom-wled.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/video/backlight/qcom-wled.c 
b/drivers/video/backlight/qcom-wled.c
index 29910e603c42..27e8949c7922 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -1526,6 +1526,12 @@ static int wled_configure(struct wled *wled)
                                                     "qcom,enabled-strings",
                                                     sizeof(u32));
        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;
+               }
+
                rc = of_property_read_u32_array(dev->of_node,
                                                "qcom,enabled-strings",
                                                wled->cfg.enabled_strings,
@@ -1537,6 +1543,14 @@ static int wled_configure(struct wled *wled)
                        return -EINVAL;
                }
 
+               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;
+                       }
+               }
+
                cfg->num_strings = string_len;
        }
 
-- 
2.33.0