[PATCH] Documentation: laptops: freefall.c: Cleaning up missing null-terminate in conjunction with strncpy

[PATCH] Documentation: laptops: freefall.c: Cleaning up missing null-terminate in conjunction with strncpy

[Rickard Strandqvist]

Added a guaranteed null-terminate after call to strncpy.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
---
 Documentation/laptops/freefall.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Documentation/laptops/freefall.c b/Documentation/laptops/freefall.c
index aab2ff0..113d004 100644
--- a/Documentation/laptops/freefall.c
+++ b/Documentation/laptops/freefall.c
@@ -33,8 +33,10 @@ static int set_unload_heads_path(char *device)
 
 	if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
 		return -EINVAL;
-	strncpy(devname, device + 5, sizeof(devname) - 1);
-	strncpy(device_path, device, sizeof(device_path) - 1);
+	strncpy(devname, device + 5, sizeof(devname));
+	devname[sizeof(devname) - 1] = '\0';
+	strncpy(device_path, device, sizeof(device_path));
+	device_path[sizeof(device_path) - 1] = '\0';
 
 	snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
 				"/sys/block/%s/device/unload_heads", devname);
-- 
1.7.10.4

Re: [PATCH] Documentation: laptops: freefall.c: Cleaning up missing null-terminate in conjunction with strncpy

[Pavel Machek]

On Sun 2014-07-27 16:40:43, Rickard Strandqvist wrote:
> Added a guaranteed null-terminate after call to strncpy.
> 
> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>

Acked-by: Pavel Machek <pavel@ucw.cz>

Re: [PATCH] Documentation: laptops: freefall.c: Cleaning up missing null-terminate in conjunction with strncpy

[Randy Dunlap]

On 07/27/14 07:40, Rickard Strandqvist wrote:
> Added a guaranteed null-terminate after call to strncpy.
> 
> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
> ---
>  Documentation/laptops/freefall.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/laptops/freefall.c b/Documentation/laptops/freefall.c
> index aab2ff0..113d004 100644
> --- a/Documentation/laptops/freefall.c
> +++ b/Documentation/laptops/freefall.c
> @@ -33,8 +33,10 @@ static int set_unload_heads_path(char *device)
>  
>  	if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
>  		return -EINVAL;
> -	strncpy(devname, device + 5, sizeof(devname) - 1);
> -	strncpy(device_path, device, sizeof(device_path) - 1);

Maybe I am overlooking something here, but what was wrong with
the - 1 (2 times) above?  and then just add the 2 lines below that set the
last byte to '\0'?

> +	strncpy(devname, device + 5, sizeof(devname));
> +	devname[sizeof(devname) - 1] = '\0';
> +	strncpy(device_path, device, sizeof(device_path));
> +	device_path[sizeof(device_path) - 1] = '\0';
>  
>  	snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
>  				"/sys/block/%s/device/unload_heads", devname);
> 


-- 
~Randy

Re: [PATCH] Documentation: laptops: freefall.c: Cleaning up missing null-terminate in conjunction with strncpy

[Pavel Machek]

On Sun 2014-07-27 16:03:44, Randy Dunlap wrote:
> On 07/27/14 07:40, Rickard Strandqvist wrote:
> > Added a guaranteed null-terminate after call to strncpy.
> > 
> > Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
> > ---
> >  Documentation/laptops/freefall.c |    6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/Documentation/laptops/freefall.c b/Documentation/laptops/freefall.c
> > index aab2ff0..113d004 100644
> > --- a/Documentation/laptops/freefall.c
> > +++ b/Documentation/laptops/freefall.c
> > @@ -33,8 +33,10 @@ static int set_unload_heads_path(char *device)
> >  
> >  	if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
> >  		return -EINVAL;
> > -	strncpy(devname, device + 5, sizeof(devname) - 1);
> > -	strncpy(device_path, device, sizeof(device_path) - 1);
> 
> Maybe I am overlooking something here, but what was wrong with
> the - 1 (2 times) above?  and then just add the 2 lines below that set the
> last byte to '\0'?

Actually device_path is static, so it will be zero-initialized and
explicit set is not neccessary AFAICT.

(devname is auto -> needs explicit set).
								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[PATCHv2] Documentation: laptops: freefall.c: Fix missing null-termination

[Pavel Machek]

devname is automatic variable, so it may not contain 0 at the last
position.

Reported-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

diff --git a/Documentation/laptops/freefall.c b/Documentation/laptops/freefall.c
index aab2ff0..93a7ebf 100644
--- a/Documentation/laptops/freefall.c
+++ b/Documentation/laptops/freefall.c
@@ -29,7 +29,8 @@ static const char app_name[] = "FREE FALL";
 
 static int set_unload_heads_path(char *device)
 {
-	char devname[64];
+	/* static for zero termination */
+	static char devname[64];
 
 	if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
 		return -EINVAL;


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[PATCHv3] Documentation: laptops: freefall.c: simplify to avoid null-termination problems

[Pavel Machek]

Copying to local variable is actually not neccessary, if all we need
to do is snprintf(). This also removes problem where devname could be
missing zero termination.

Reported-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

diff --git a/Documentation/laptops/freefall.c b/Documentation/laptops/freefall.c
index aab2ff0..5e44b20 100644
--- a/Documentation/laptops/freefall.c
+++ b/Documentation/laptops/freefall.c
@@ -29,15 +29,12 @@ static const char app_name[] = "FREE FALL";
 
 static int set_unload_heads_path(char *device)
 {
-	char devname[64];
-
 	if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
 		return -EINVAL;
-	strncpy(devname, device + 5, sizeof(devname) - 1);
 	strncpy(device_path, device, sizeof(device_path) - 1);
 
 	snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
-				"/sys/block/%s/device/unload_heads", devname);
+				"/sys/block/%s/device/unload_heads", device+5);
 	return 0;
 }
 



-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCHv3] Documentation: laptops: freefall.c: simplify to avoid null-termination problems

[Randy Dunlap]

On 07/28/14 04:13, Pavel Machek wrote:
> 
> Copying to local variable is actually not neccessary, if all we need
> to do is snprintf(). This also removes problem where devname could be
> missing zero termination.
> 
> Reported-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
> Signed-off-by: Pavel Machek <pavel@ucw.cz>

Applied.  Thanks.

> 
> diff --git a/Documentation/laptops/freefall.c b/Documentation/laptops/freefall.c
> index aab2ff0..5e44b20 100644
> --- a/Documentation/laptops/freefall.c
> +++ b/Documentation/laptops/freefall.c
> @@ -29,15 +29,12 @@ static const char app_name[] = "FREE FALL";
>  
>  static int set_unload_heads_path(char *device)
>  {
> -	char devname[64];
> -
>  	if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
>  		return -EINVAL;
> -	strncpy(devname, device + 5, sizeof(devname) - 1);
>  	strncpy(device_path, device, sizeof(device_path) - 1);
>  
>  	snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
> -				"/sys/block/%s/device/unload_heads", devname);
> +				"/sys/block/%s/device/unload_heads", device+5);
>  	return 0;
>  }
>  
> 
> 
> 


-- 
~Randy