[U-Boot] [PATCH] x86: zImage: avoid potential NULL dereference

[Tom Rini]

On Sat, Apr 15, 2017 at 03:58:55PM +0200, Heinrich Schuchardt wrote:

> If bootargs is not assigned getenv("bootargs") will
> return NULL.
> Some part of the code is checking for this condition.
> Other parts dereference a possible NULL pointer.
> 
> The problem was indicated by cppcheck.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
>  arch/x86/lib/zimage.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/lib/zimage.c b/arch/x86/lib/zimage.c
> index aafbeb01f9..9b564340a6 100644
> --- a/arch/x86/lib/zimage.c
> +++ b/arch/x86/lib/zimage.c
> @@ -48,12 +48,14 @@ static void build_command_line(char *command_line, int auto_boot)
>  
>  	command_line[0] = '\0';
>  
> -	env_command_line =  getenv("bootargs");
> +	env_command_line = getenv("bootargs");
> +
> +	if (!env_command_line)
> +		env_command_line = "";
>  
>  	/* set console= argument if we use a serial console */
>  	if (!strstr(env_command_line, "console=")) {
>  		if (!strcmp(getenv("stdout"), "serial")) {
> -
>  			/* We seem to use serial console */
>  			sprintf(command_line, "console=ttyS0,%s ",
>  				getenv("baudrate"));
> @@ -63,8 +65,7 @@ static void build_command_line(char *command_line, int auto_boot)
>  	if (auto_boot)
>  		strcat(command_line, "auto ");
>  
> -	if (env_command_line)
> -		strcat(command_line, env_command_line);
> +	strcat(command_line, env_command_line);
>  
>  	printf("Kernel command line: \"%s\"\n", command_line);
>  }

I think this is a false positive from cppcheck.  With env_command_line
set to NULL, strstr will return NULL.  The only other place we use
env_command_line is further on where we alrady have a check.  Thanks!

-- 
Tom
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