[U-Boot] [RFC/PATCH] common/command.c: Guard strchr/strlen from NULL pointer

[Sergei Shtylyov <sshtylyov@mvista.com>]

Hello.

On 24-11-2010 13:15, Thomas Weber wrote:

> Guard strchr/strlen from being called with NULL pointer.
> This line is crashing on OMAP3/Devkit8000 when command "env" is called without subcommand.

> Toolchain is Codesourcery 2010q1.

> The cmd is NULL in this case because the calling function "do_env" decremented the argc
> without checking if there are still arguments available.

> caller:
> static int do_env (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
> ...
>          /* drop initial "env" arg */
>          argc--;
>          argv++;
>
>          cp = find_cmd_tbl(argv[0], cmd_env_sub, ARRAY_SIZE(cmd_env_sub));


> Signed-off-by: Thomas Weber<weber@corscience.de>
> ---
>   common/command.c |    5 +++--
>   1 files changed, 3 insertions(+), 2 deletions(-)

> diff --git a/common/command.c b/common/command.c
> index 0020eac..03a713a 100644
> --- a/common/command.c
> +++ b/common/command.c
> @@ -105,14 +105,15 @@ cmd_tbl_t *find_cmd_tbl (const char *cmd, cmd_tbl_t *table, int table_len)
>   	cmd_tbl_t *cmdtp;
>   	cmd_tbl_t *cmdtp_temp = table;	/*Init value */
>   	const char *p;
> -	int len;
> +	int len = 0;
>   	int n_found = 0;
>
>   	/*
>   	 * Some commands allow length modifiers (like "cp.b");
>   	 * compare command name only until first dot.
>   	 */
> -	len = ((p = strchr(cmd, '.')) == NULL) ? strlen (cmd) : (p - cmd);
> +	if (cmd != NULL)
> +		len = ((p = strchr(cmd, '.')) == NULL) ? strlen (cmd) : (p - cmd);

    checkpatch.pl would complain about the space between 'strlen' and (, so 
seems a high time to fix this. Besides, it's not consistent with strchr() 
invocation where there's no space...

WBR, Sergei