[PATCH] staging: fbtft: fix out of bound access

[PATCH] staging: fbtft: fix out of bound access

[Sudip Mukherjee]

size of str is 16, but in snprintf the size was mentioned as 128.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
---
 drivers/staging/fbtft/fbtft-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
index ce64521..0af84b5 100644
--- a/drivers/staging/fbtft/fbtft-core.c
+++ b/drivers/staging/fbtft/fbtft-core.c
@@ -1096,7 +1096,7 @@ static int fbtft_init_display_dt(struct fbtft_par *par)
 			/* make debug message */
 			msg[0] = '\0';
 			for (j = 0; j < i; j++) {
-				snprintf(str, 128, " %02X", buf[j]);
+				snprintf(str, 16, " %02X", buf[j]);
 				strcat(msg, str);
 			}
 			fbtft_par_dbg(DEBUG_INIT_DISPLAY, par,
-- 
1.8.1.2

Re: [PATCH] staging: fbtft: fix out of bound access

[Joe Perches]

On Thu, 2015-06-04 at 17:12 +0530, Sudip Mukherjee wrote:
> size of str is 16, but in snprintf the size was mentioned as 128.
[]
> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
[]
> @@ -1096,7 +1096,7 @@ static int fbtft_init_display_dt(struct fbtft_par *par)
>  			/* make debug message */
>  			msg[0] = '\0';
>  			for (j = 0; j < i; j++) {
> -				snprintf(str, 128, " %02X", buf[j]);
> +				snprintf(str, 16, " %02X", buf[j]);

using sizeof(str) is probably more robust

msg isn't big enough to hold the maximum possible output.

If this is really useful, and I rather doubt it is,
it'd probably be better to use a loop to output
multiple lines, one for each register.

Re: [PATCH] staging: fbtft: fix out of bound access

[Sudip Mukherjee]

On Thu, Jun 04, 2015 at 05:12:23AM -0700, Joe Perches wrote:
> On Thu, 2015-06-04 at 17:12 +0530, Sudip Mukherjee wrote:
> > size of str is 16, but in snprintf the size was mentioned as 128.
> []
> > diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
> []
> > @@ -1096,7 +1096,7 @@ static int fbtft_init_display_dt(struct fbtft_par *par)
> >  			/* make debug message */
> >  			msg[0] = '\0';
> >  			for (j = 0; j < i; j++) {
> > -				snprintf(str, 128, " %02X", buf[j]);
> > +				snprintf(str, 16, " %02X", buf[j]);
> 
> using sizeof(str) is probably more robust
> 
> msg isn't big enough to hold the maximum possible output.
yes, it will not hold. i didn't notice msg size.
> 
> If this is really useful, and I rather doubt it is,
> it'd probably be better to use a loop to output
> multiple lines, one for each register.
I will send in a v2 doing this.

regards
sudip
> 
> 

Re: [PATCH] staging: fbtft: fix out of bound access

[Dan Carpenter]

On Thu, Jun 04, 2015 at 05:12:01PM +0530, Sudip Mukherjee wrote:
> size of str is 16, but in snprintf the size was mentioned as 128.
> 
> Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
> ---
>  drivers/staging/fbtft/fbtft-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
> index ce64521..0af84b5 100644
> --- a/drivers/staging/fbtft/fbtft-core.c
> +++ b/drivers/staging/fbtft/fbtft-core.c
> @@ -1096,7 +1096,7 @@ static int fbtft_init_display_dt(struct fbtft_par *par)
>  			/* make debug message */
>  			msg[0] = '\0';
>  			for (j = 0; j < i; j++) {
> -				snprintf(str, 128, " %02X", buf[j]);
> +				snprintf(str, 16, " %02X", buf[j]);

Good eye.  How did you find this?

The good news is buf[j] is <= 0xFFFF so it won't actually overflow.  Who
knows why it is zero padded 2 spaces...  But use sizeof(str) instead of
16.

regards,
dan carpenter

Re: [PATCH] staging: fbtft: fix out of bound access

[Sudip Mukherjee]

On Thu, Jun 04, 2015 at 03:36:31PM +0300, Dan Carpenter wrote:
> On Thu, Jun 04, 2015 at 05:12:01PM +0530, Sudip Mukherjee wrote:
> > size of str is 16, but in snprintf the size was mentioned as 128.
> > 
> > Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
> > ---
<snip>
> Good eye.  How did you find this?
:) not me. cppcheck. 
> 
> The good news is buf[j] is <= 0xFFFF so it won't actually overflow.  Who
> knows why it is zero padded 2 spaces...  But use sizeof(str) instead of
> 16.
but my v2 will remove the use of msg and str.

regards
sudip
> 
> regards,
> dan carpenter
>