[PATCH] media: rc: Use scnprintf() for avoiding potential buffer overflow

[PATCH] media: rc: Use scnprintf() for avoiding potential buffer overflow

[Takashi Iwai]

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 drivers/media/rc/nuvoton-cir.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/rc/nuvoton-cir.c b/drivers/media/rc/nuvoton-cir.c
index 5c2cd8d2d155..48a69bf23236 100644
--- a/drivers/media/rc/nuvoton-cir.c
+++ b/drivers/media/rc/nuvoton-cir.c
@@ -230,10 +230,10 @@ static ssize_t wakeup_data_show(struct device *dev,
 	for (i = 0; i < fifo_len; i++) {
 		duration = nvt_cir_wake_reg_read(nvt, CIR_WAKE_RD_FIFO_ONLY);
 		duration = (duration & BUF_LEN_MASK) * SAMPLE_PERIOD;
-		buf_len += snprintf(buf + buf_len, PAGE_SIZE - buf_len,
+		buf_len += scnprintf(buf + buf_len, PAGE_SIZE - buf_len,
 				    "%d ", duration);
 	}
-	buf_len += snprintf(buf + buf_len, PAGE_SIZE - buf_len, "\n");
+	buf_len += scnprintf(buf + buf_len, PAGE_SIZE - buf_len, "\n");
 
 	spin_unlock_irqrestore(&nvt->lock, flags);
 
-- 
2.16.4

Re: [PATCH] media: rc: Use scnprintf() for avoiding potential buffer overflow

[Takashi Iwai]

On Wed, 11 Mar 2020 08:47:06 +0100,
Takashi Iwai wrote:
> 
> Since snprintf() returns the would-be-output size instead of the
> actual output size, the succeeding calls may go beyond the given
> buffer limit.  Fix it by replacing with scnprintf().
> 
> Signed-off-by: Takashi Iwai <tiwai@suse.de>

A gentle reminder for this forgotten patch.
Let me know if any further changes are needed.


thanks,

Takashi

> ---
>  drivers/media/rc/nuvoton-cir.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/rc/nuvoton-cir.c b/drivers/media/rc/nuvoton-cir.c
> index 5c2cd8d2d155..48a69bf23236 100644
> --- a/drivers/media/rc/nuvoton-cir.c
> +++ b/drivers/media/rc/nuvoton-cir.c
> @@ -230,10 +230,10 @@ static ssize_t wakeup_data_show(struct device *dev,
>  	for (i = 0; i < fifo_len; i++) {
>  		duration = nvt_cir_wake_reg_read(nvt, CIR_WAKE_RD_FIFO_ONLY);
>  		duration = (duration & BUF_LEN_MASK) * SAMPLE_PERIOD;
> -		buf_len += snprintf(buf + buf_len, PAGE_SIZE - buf_len,
> +		buf_len += scnprintf(buf + buf_len, PAGE_SIZE - buf_len,
>  				    "%d ", duration);
>  	}
> -	buf_len += snprintf(buf + buf_len, PAGE_SIZE - buf_len, "\n");
> +	buf_len += scnprintf(buf + buf_len, PAGE_SIZE - buf_len, "\n");
>  
>  	spin_unlock_irqrestore(&nvt->lock, flags);
>  
> -- 
> 2.16.4
> 

Re: [PATCH] media: rc: Use scnprintf() for avoiding potential buffer overflow

[Sean Young]

On Thu, Mar 19, 2020 at 04:57:42PM +0100, Takashi Iwai wrote:
> On Wed, 11 Mar 2020 08:47:06 +0100,
> Takashi Iwai wrote:
> > 
> > Since snprintf() returns the would-be-output size instead of the
> > actual output size, the succeeding calls may go beyond the given
> > buffer limit.  Fix it by replacing with scnprintf().
> > 
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> 
> A gentle reminder for this forgotten patch.
> Let me know if any further changes are needed.

Thank you for your reminder. The changes look good, unfortunately they
missed the deadline for v5.7. I handle them after the next merge window.

Thanks,

Sean

> 
> 
> thanks,
> 
> Takashi
> 
> > ---
> >  drivers/media/rc/nuvoton-cir.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/media/rc/nuvoton-cir.c b/drivers/media/rc/nuvoton-cir.c
> > index 5c2cd8d2d155..48a69bf23236 100644
> > --- a/drivers/media/rc/nuvoton-cir.c
> > +++ b/drivers/media/rc/nuvoton-cir.c
> > @@ -230,10 +230,10 @@ static ssize_t wakeup_data_show(struct device *dev,
> >  	for (i = 0; i < fifo_len; i++) {
> >  		duration = nvt_cir_wake_reg_read(nvt, CIR_WAKE_RD_FIFO_ONLY);
> >  		duration = (duration & BUF_LEN_MASK) * SAMPLE_PERIOD;
> > -		buf_len += snprintf(buf + buf_len, PAGE_SIZE - buf_len,
> > +		buf_len += scnprintf(buf + buf_len, PAGE_SIZE - buf_len,
> >  				    "%d ", duration);
> >  	}
> > -	buf_len += snprintf(buf + buf_len, PAGE_SIZE - buf_len, "\n");
> > +	buf_len += scnprintf(buf + buf_len, PAGE_SIZE - buf_len, "\n");
> >  
> >  	spin_unlock_irqrestore(&nvt->lock, flags);
> >  
> > -- 
> > 2.16.4
> >