[PATCH] regulator: s5m8767: fix get_register() error handling

[PATCH] regulator: s5m8767: fix get_register() error handling

[Arnd Bergmann]

The s5m8767_pmic_probe() function calls s5m8767_get_register() to
read data without checking the return code, which produces a compile-time
warning when that data is accessed:

drivers/regulator/s5m8767.c: In function 's5m8767_pmic_probe':
drivers/regulator/s5m8767.c:924:7: error: 'enable_reg' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/regulator/s5m8767.c:944:30: error: 'enable_val' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This changes the s5m8767_get_register() function to return a -EINVAL
not just for an invalid register number but also for an invalid
regulator number, as both would result in returning uninitialized
data. The s5m8767_pmic_probe() function is then changed accordingly
to fail on a read error, as all the other callers of s5m8767_get_register()
already do.

In practice this probably cannot happen, as we don't call
s5m8767_get_register() with invalid arguments, but the gcc
warning seems valid in principle, in terms writing safe
error checking.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 9c4c60554acf ("regulator: s5m8767: Convert to use regulator_[enable|disable|is_enabled]_regmap")
---
 drivers/regulator/s5m8767.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/regulator/s5m8767.c b/drivers/regulator/s5m8767.c
index 58f5d3b8e981..27343e1c43ef 100644
--- a/drivers/regulator/s5m8767.c
+++ b/drivers/regulator/s5m8767.c
@@ -202,9 +202,10 @@ static int s5m8767_get_register(struct s5m8767_info *s5m8767, int reg_id,
 		}
 	}
 
-	if (i < s5m8767->num_regulators)
-		*enable_ctrl =
-		s5m8767_opmode_reg[reg_id][mode] << S5M8767_ENCTRL_SHIFT;
+	if (i >= s5m8767->num_regulators)
+		return -EINVAL;
+
+	*enable_ctrl = s5m8767_opmode_reg[reg_id][mode] << S5M8767_ENCTRL_SHIFT;
 
 	return 0;
 }
@@ -937,8 +938,12 @@ static int s5m8767_pmic_probe(struct platform_device *pdev)
 			else
 				regulators[id].vsel_mask = 0xff;
 
-			s5m8767_get_register(s5m8767, id, &enable_reg,
+			ret = s5m8767_get_register(s5m8767, id, &enable_reg,
 					     &enable_val);
+			if (ret) {
+				dev_err(s5m8767->dev, "error reading registers\n");
+				return ret;
+			}
 			regulators[id].enable_reg = enable_reg;
 			regulators[id].enable_mask = S5M8767_ENCTRL_MASK;
 			regulators[id].enable_val = enable_val;
-- 
2.7.0

Re: [PATCH] regulator: s5m8767: fix get_register() error handling

[Krzysztof Kozlowski]

On 16.02.2016 23:53, Arnd Bergmann wrote:
> The s5m8767_pmic_probe() function calls s5m8767_get_register() to
> read data without checking the return code, which produces a compile-time
> warning when that data is accessed:
> 
> drivers/regulator/s5m8767.c: In function 's5m8767_pmic_probe':
> drivers/regulator/s5m8767.c:924:7: error: 'enable_reg' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> drivers/regulator/s5m8767.c:944:30: error: 'enable_val' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 
> This changes the s5m8767_get_register() function to return a -EINVAL
> not just for an invalid register number but also for an invalid
> regulator number, as both would result in returning uninitialized
> data. The s5m8767_pmic_probe() function is then changed accordingly
> to fail on a read error, as all the other callers of s5m8767_get_register()
> already do.
> 
> In practice this probably cannot happen, as we don't call
> s5m8767_get_register() with invalid arguments, but the gcc
> warning seems valid in principle, in terms writing safe
> error checking.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Fixes: 9c4c60554acf ("regulator: s5m8767: Convert to use regulator_[enable|disable|is_enabled]_regmap")
> ---
>  drivers/regulator/s5m8767.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 

Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>

Best regards,
Krzysztof

Applied "regulator: s5m8767: fix get_register() error handling" to the regulator tree

[Mark Brown]

The patch

   regulator: s5m8767: fix get_register() error handling

has been applied to the regulator tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From e07ff9434167981c993a26d2edbbcb8e13801dbb Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Tue, 16 Feb 2016 15:53:11 +0100
Subject: [PATCH] regulator: s5m8767: fix get_register() error handling

The s5m8767_pmic_probe() function calls s5m8767_get_register() to
read data without checking the return code, which produces a compile-time
warning when that data is accessed:

drivers/regulator/s5m8767.c: In function 's5m8767_pmic_probe':
drivers/regulator/s5m8767.c:924:7: error: 'enable_reg' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/regulator/s5m8767.c:944:30: error: 'enable_val' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This changes the s5m8767_get_register() function to return a -EINVAL
not just for an invalid register number but also for an invalid
regulator number, as both would result in returning uninitialized
data. The s5m8767_pmic_probe() function is then changed accordingly
to fail on a read error, as all the other callers of s5m8767_get_register()
already do.

In practice this probably cannot happen, as we don't call
s5m8767_get_register() with invalid arguments, but the gcc
warning seems valid in principle, in terms writing safe
error checking.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 9c4c60554acf ("regulator: s5m8767: Convert to use regulator_[enable|disable|is_enabled]_regmap")
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/regulator/s5m8767.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/regulator/s5m8767.c b/drivers/regulator/s5m8767.c
index 58f5d3b8e981..27343e1c43ef 100644
--- a/drivers/regulator/s5m8767.c
+++ b/drivers/regulator/s5m8767.c
@@ -202,9 +202,10 @@ static int s5m8767_get_register(struct s5m8767_info *s5m8767, int reg_id,
 		}
 	}
 
-	if (i < s5m8767->num_regulators)
-		*enable_ctrl =
-		s5m8767_opmode_reg[reg_id][mode] << S5M8767_ENCTRL_SHIFT;
+	if (i >= s5m8767->num_regulators)
+		return -EINVAL;
+
+	*enable_ctrl = s5m8767_opmode_reg[reg_id][mode] << S5M8767_ENCTRL_SHIFT;
 
 	return 0;
 }
@@ -937,8 +938,12 @@ static int s5m8767_pmic_probe(struct platform_device *pdev)
 			else
 				regulators[id].vsel_mask = 0xff;
 
-			s5m8767_get_register(s5m8767, id, &enable_reg,
+			ret = s5m8767_get_register(s5m8767, id, &enable_reg,
 					     &enable_val);
+			if (ret) {
+				dev_err(s5m8767->dev, "error reading registers\n");
+				return ret;
+			}
 			regulators[id].enable_reg = enable_reg;
 			regulators[id].enable_mask = S5M8767_ENCTRL_MASK;
 			regulators[id].enable_val = enable_val;
-- 
2.7.0