linux-kernel - [PATCH] regulator: s5m8767: Bounds check id indexing into arrays

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Message-Id: <20230128005358.never.313-kees@kernel.org>
Date:   Fri, 27 Jan 2023 16:53:58 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: [PATCH] regulator: s5m8767: Bounds check id indexing into arrays

The compiler has no way to know if "id" is within the array bounds of
the regulators array. Add a check for this and a build-time check that
the regulators and reg_voltage_map arrays are sized the same. Seen with
GCC 13:

../drivers/regulator/s5m8767.c: In function 's5m8767_pmic_probe':
../drivers/regulator/s5m8767.c:936:35: warning: array subscript [0, 36] is outside array bounds of 'struct regulator_desc[37]' [-Warray-bounds=]
  936 |                         regulators[id].vsel_reg =
      |                         ~~~~~~~~~~^~~~

Cc: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Liam Girdwood <lgirdwood@...il.com>
Cc: Mark Brown <broonie@...nel.org>
Cc: linux-samsung-soc@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/regulator/s5m8767.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/regulator/s5m8767.c b/drivers/regulator/s5m8767.c
index 35269f998210..754c6fcc6e64 100644
--- a/drivers/regulator/s5m8767.c
+++ b/drivers/regulator/s5m8767.c
@@ -923,10 +923,14 @@ static int s5m8767_pmic_probe(struct platform_device *pdev)
 
 	for (i = 0; i < pdata->num_regulators; i++) {
 		const struct sec_voltage_desc *desc;
-		int id = pdata->regulators[i].id;
+		unsigned int id = pdata->regulators[i].id;
 		int enable_reg, enable_val;
 		struct regulator_dev *rdev;
 
+		BUILD_BUG_ON(ARRAY_SIZE(regulators) != ARRAY_SIZE(reg_voltage_map));
+		if (WARN_ON_ONCE(id >= ARRAY_SIZE(regulators)))
+			continue;
+
 		desc = reg_voltage_map[id];
 		if (desc) {
 			regulators[id].n_voltages =
-- 
2.34.1