[PATCH] video: fbdev: pvr2fb: initialize variables

[PATCH] video: fbdev: pvr2fb: initialize variables

[trix]

From: Tom Rix <trix@redhat.com>

clang static analysis reports this repesentative error

pvr2fb.c:1049:2: warning: 1st function call argument
  is an uninitialized value [core.CallAndMessage]
        if (*cable_arg)
        ^~~~~~~~~~~~~~~

Problem is that cable_arg depends on the input loop to
set the cable_arg[0].  If it does not, then some random
value from the stack is used.

A similar problem exists for output_arg.

So initialize cable_arg and output_arg.

Signed-off-by: Tom Rix <trix@redhat.com>
---
 drivers/video/fbdev/pvr2fb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/fbdev/pvr2fb.c b/drivers/video/fbdev/pvr2fb.c
index 2d9f69b93392..f4add36cb5f4 100644
--- a/drivers/video/fbdev/pvr2fb.c
+++ b/drivers/video/fbdev/pvr2fb.c
@@ -1028,6 +1028,8 @@ static int __init pvr2fb_setup(char *options)
 	if (!options || !*options)
 		return 0;
 
+	cable_arg[0] = output_arg[0] = 0;
+
 	while ((this_opt = strsep(&options, ","))) {
 		if (!*this_opt)
 			continue;
-- 
2.18.1

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Re: [PATCH] video: fbdev: pvr2fb: initialize variables

[Arnd Bergmann]

On Mon, Jul 20, 2020 at 9:19 PM <trix@redhat.com> wrote:
>
> From: Tom Rix <trix@redhat.com>
>
> clang static analysis reports this repesentative error
>
> pvr2fb.c:1049:2: warning: 1st function call argument
>   is an uninitialized value [core.CallAndMessage]
>         if (*cable_arg)
>         ^~~~~~~~~~~~~~~
>
> Problem is that cable_arg depends on the input loop to
> set the cable_arg[0].  If it does not, then some random
> value from the stack is used.
>
> A similar problem exists for output_arg.
>
> So initialize cable_arg and output_arg.

Adding a zero-initialization is almost never the correct way to
deal with these warnings, so one has to be careful doing this.

I checked this file, and your patch is absolutely correct here. ;-)

> Signed-off-by: Tom Rix <trix@redhat.com>

Acked-by: Arnd Bergmann <arnd@arndb.de>
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Re: [PATCH] video: fbdev: pvr2fb: initialize variables

[Sam Ravnborg]

Hi Tom,

On Mon, Jul 20, 2020 at 12:18:45PM -0700, trix@redhat.com wrote:
> From: Tom Rix <trix@redhat.com>
> 
> clang static analysis reports this repesentative error
> 
> pvr2fb.c:1049:2: warning: 1st function call argument
>   is an uninitialized value [core.CallAndMessage]
>         if (*cable_arg)
>         ^~~~~~~~~~~~~~~
> 
> Problem is that cable_arg depends on the input loop to
> set the cable_arg[0].  If it does not, then some random
> value from the stack is used.
> 
> A similar problem exists for output_arg.
> 
> So initialize cable_arg and output_arg.
> 
> Signed-off-by: Tom Rix <trix@redhat.com>

Thanks, applied to drm-misc-next.

	Sam

> ---
>  drivers/video/fbdev/pvr2fb.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/video/fbdev/pvr2fb.c b/drivers/video/fbdev/pvr2fb.c
> index 2d9f69b93392..f4add36cb5f4 100644
> --- a/drivers/video/fbdev/pvr2fb.c
> +++ b/drivers/video/fbdev/pvr2fb.c
> @@ -1028,6 +1028,8 @@ static int __init pvr2fb_setup(char *options)
>  	if (!options || !*options)
>  		return 0;
>  
> +	cable_arg[0] = output_arg[0] = 0;
> +
>  	while ((this_opt = strsep(&options, ","))) {
>  		if (!*this_opt)
>  			continue;
> -- 
> 2.18.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
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