linux-kernel - Re: [PATCH] media: si2165: fix a missing check of return value

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Message-ID: <40956844-c18d-31d2-1f2c-e164dfe82ecf@gentoo.org>
Date:   Thu, 20 Dec 2018 14:46:52 +0100
From:   Matthias Schwarzott <zzam@...too.org>
To:     Kangjie Lu <kjlu@....edu>
Cc:     pakki001@....edu, Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: si2165: fix a missing check of return value

Am 20.12.18 um 09:12 schrieb Kangjie Lu:
> si2165_readreg8() may fail. Looking into si2165_readreg8(), we will find
> that "val_tmp" will be an uninitialized value when regmap_read() fails.
> "val_tmp" is then assigned to "val". So if si2165_readreg8() fails,
> "val" will be a random value. Further use will lead to undefined
> behaviors. The fix checks if si2165_readreg8() fails, and if so, returns
> "-EINVAL".
> 
Good catch. I reviewed it.
See below.

> Signed-off-by: Kangjie Lu <kjlu@....edu>
> ---
>  drivers/media/dvb-frontends/si2165.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/dvb-frontends/si2165.c b/drivers/media/dvb-frontends/si2165.c
> index feacd8da421d..c134f312fa5b 100644
> --- a/drivers/media/dvb-frontends/si2165.c
> +++ b/drivers/media/dvb-frontends/si2165.c
> @@ -275,18 +275,20 @@ static u32 si2165_get_fe_clk(struct si2165_state *state)
>  
>  static int si2165_wait_init_done(struct si2165_state *state)
>  {
> -	int ret = -EINVAL;
> +	int ret;
>  	u8 val = 0;
>  	int i;
>  
>  	for (i = 0; i < 3; ++i) {
> -		si2165_readreg8(state, REG_INIT_DONE, &val);
> +		ret = si2165_readreg8(state, REG_INIT_DONE, &val);
> +		if (ret < 0)
> +			return -EINVAL;
This code should return "ret" instead of "-EINVAL".

>  		if (val == 0x01)
>  			return 0;
>  		usleep_range(1000, 50000);
>  	}
>  	dev_err(&state->client->dev, "init_done was not set\n");
> -	return ret;
> +	return -EINVAL;

Here I am not sure if -ETIMEDOUT would be a better return code.

>  }
>  
>  static int si2165_upload_firmware_block(struct si2165_state *state,
>