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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Marijn Suijten <marijn.suijten@somainline.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@somainline.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Lee Jones <lee.jones@linaro.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0344/1039] backlight: qcom-wled: Validate enabled string indices in DT
Date:   Mon, 24 Jan 2022 19:35:33 +0100
Message-Id: <20220124184136.861020501@linuxfoundation.org>
In-Reply-To: <20220124184125.121143506@linuxfoundation.org>
References: <20220124184125.121143506@linuxfoundation.org>
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From: Marijn Suijten <marijn.suijten@somainline.org>

[ 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@somainline.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211115203459.1634079-2-marijn.suijten@somainline.org
Signed-off-by: Sasha Levin <sashal@kernel.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 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