[PATCH v2] hwrng: imx-rngc - check return value of clk_prepare_enable()

[PATCH v2] hwrng: imx-rngc - check return value of clk_prepare_enable()

[Ma Yukun]

clk_prepare_enable() can fail here and its return value is currently
ignored. If the clock fails to enable, the probe continues to read
from the hardware registers without a clock, which can cause a bus
hang or external abort.

Check the return value and fail probe if the clock cannot be enabled.

Fixes: 1d5449445bd0 ("hwrng: mx-rngc - add a driver for Freescale RNGC")
Signed-off-by: Ma Yukun <0x4fe6@gmail.com>
---
v2: fix patch formatting, add missing context line

 drivers/char/hw_random/imx-rngc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c
index 7693328f1..58bdc7a6b 100644
--- a/drivers/char/hw_random/imx-rngc.c
+++ b/drivers/char/hw_random/imx-rngc.c
@@ -266,7 +266,9 @@ static int __init imx_rngc_probe(struct platform_device *pdev)
 	if (irq < 0)
 		return irq;
 
-	clk_prepare_enable(rngc->clk);
+	ret = clk_prepare_enable(rngc->clk);
+	if (ret)
+		return ret;
 
 	ver_id = readl(rngc->base + RNGC_VER_ID);
 	rng_type = FIELD_GET(RNG_TYPE, ver_id);
-- 
2.43.0

Re: [PATCH v2] hwrng: imx-rngc - check return value of clk_prepare_enable()

[Martin Kaiser]

Thus wrote Ma Yukun (0x4fe6@gmail.com):

> clk_prepare_enable() can fail here and its return value is currently
> ignored. If the clock fails to enable, the probe continues to read
> from the hardware registers without a clock, which can cause a bus
> hang or external abort.

> Check the return value and fail probe if the clock cannot be enabled.

> Fixes: 1d5449445bd0 ("hwrng: mx-rngc - add a driver for Freescale RNGC")
> Signed-off-by: Ma Yukun <0x4fe6@gmail.com>
> ---
> v2: fix patch formatting, add missing context line

>  drivers/char/hw_random/imx-rngc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

> diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c
> index 7693328f1..58bdc7a6b 100644
> --- a/drivers/char/hw_random/imx-rngc.c
> +++ b/drivers/char/hw_random/imx-rngc.c
> @@ -266,7 +266,9 @@ static int __init imx_rngc_probe(struct platform_device *pdev)
>  	if (irq < 0)
>  		return irq;

> -	clk_prepare_enable(rngc->clk);
> +	ret = clk_prepare_enable(rngc->clk);
> +	if (ret)
> +		return ret;

>  	ver_id = readl(rngc->base + RNGC_VER_ID);
>  	rng_type = FIELD_GET(RNG_TYPE, ver_id);
> -- 
> 2.43.0

This has already been fixed.

https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git/commit/?id=8ba2b068e1b3607289ba5778e4c27c167fdbfee6