linux-kernel - [PATCH v3 1/9] backlight: qcom-wled: Validate enabled string indices in DT

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Date:   Mon, 15 Nov 2021 21:34:51 +0100
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     phone-devel@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>
Cc:     ~postmarketos/upstreaming@...ts.sr.ht,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Martin Botka <martin.botka@...ainline.org>,
        Jami Kettunen <jami.kettunen@...ainline.org>,
        Pavel Dubrova <pashadubrova@...il.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Kiran Gunda <kgunda@...eaurora.org>,
        Bryan Wu <cooloney@...il.com>, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org
Subject: [PATCH v3 1/9] backlight: qcom-wled: Validate enabled string indices in DT

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@...ainline.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>
Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>
---
 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 d094299c2a48..8a42ed89c59c 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;
 }
 
-- 
2.33.1