LinuxTV Patchwork [v2] media: si2165: fix a missing check of return value

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Submitter Kangjie Lu
Date Dec. 21, 2018, 4:54 a.m.
Message ID <20181221045403.59303-1-kjlu@umn.edu>
Download mbox | patch
Permalink /patch/53613/
State Accepted
Delegated to: Sean Young
Headers show

Comments

Kangjie Lu - Dec. 21, 2018, 4:54 a.m.
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
its error code upstream.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
 drivers/media/dvb-frontends/si2165.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)
Matthias Schwarzott - Dec. 21, 2018, 8:24 a.m.
Am 21.12.18 um 05:54 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
> its error code upstream.
> 
> Signed-off-by: Kangjie Lu <kjlu@umn.edu>

Reviewed-by: Matthias Schwarzott <zzam@gentoo.org>

> ---
>  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..d55d8f169dca 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 ret;
>  		if (val == 0x01)
>  			return 0;
>  		usleep_range(1000, 50000);
>  	}
>  	dev_err(&state->client->dev, "init_done was not set\n");
> -	return ret;
> +	return -EINVAL;
>  }
>  
>  static int si2165_upload_firmware_block(struct si2165_state *state,
>
Sean Young - March 5, 2019, 9:17 p.m.
On Fri, Dec 21, 2018 at 09:24:46AM +0100, Matthias Schwarzott wrote:
> Am 21.12.18 um 05:54 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
> > its error code upstream.
> > 
> > Signed-off-by: Kangjie Lu <kjlu@umn.edu>
> 
> Reviewed-by: Matthias Schwarzott <zzam@gentoo.org>

Unless it is tested on the actual hardware we can't apply this. This could
introduce regressions.

Sean

> 
> > ---
> >  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..d55d8f169dca 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 ret;
> >  		if (val == 0x01)
> >  			return 0;
> >  		usleep_range(1000, 50000);
> >  	}
> >  	dev_err(&state->client->dev, "init_done was not set\n");
> > -	return ret;
> > +	return -EINVAL;
> >  }
> >  
> >  static int si2165_upload_firmware_block(struct si2165_state *state,
> >
Matthias Schwarzott - March 6, 2019, 9:36 p.m.
Am 05.03.19 um 22:17 schrieb Sean Young:
> On Fri, Dec 21, 2018 at 09:24:46AM +0100, Matthias Schwarzott wrote:
>> Am 21.12.18 um 05:54 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
>>> its error code upstream.
>>>
>>> Signed-off-by: Kangjie Lu <kjlu@umn.edu>
>>
>> Reviewed-by: Matthias Schwarzott <zzam@gentoo.org>
> 
> Unless it is tested on the actual hardware we can't apply this. This could
> introduce regressions.
> 

I tested it on a Hauppauge WinTV-HVR5500 tuning to DVB-C.

Regards
Matthias

Tested-by: Matthias Schwarzott <zzam@gentoo.org>

> Sean
> 
>>
>>> ---
>>>  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..d55d8f169dca 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 ret;
>>>  		if (val == 0x01)
>>>  			return 0;
>>>  		usleep_range(1000, 50000);
>>>  	}
>>>  	dev_err(&state->client->dev, "init_done was not set\n");
>>> -	return ret;
>>> +	return -EINVAL;
>>>  }
>>>  
>>>  static int si2165_upload_firmware_block(struct si2165_state *state,
>>>
>

Patch

diff --git a/drivers/media/dvb-frontends/si2165.c b/drivers/media/dvb-frontends/si2165.c
index feacd8da421d..d55d8f169dca 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 ret;
 		if (val == 0x01)
 			return 0;
 		usleep_range(1000, 50000);
 	}
 	dev_err(&state->client->dev, "init_done was not set\n");
-	return ret;
+	return -EINVAL;
 }
 
 static int si2165_upload_firmware_block(struct si2165_state *state,

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