[PATCH] ash: fix incorrect path in describe_command

[Denys Vlasenko]

On Fri, May 26, 2017 at 9:31 AM, Youfu Zhang <zhangyoufu at gmail.com> wrote:
> $ PATH=/extra/path:/usr/sbin:/usr/bin:/sbin:/bin \
>> busybox sh -xc 'command -V ls; command -V ls; command -Vp ls; command -vp ls'
> + command -V ls
> ls is /bin/ls
> + command -V ls
> ls is a tracked alias for /bin/ls
> + command -Vp ls
> ls is a tracked alias for (null)
> + command -vp ls
> Segmentation fault
>
> describe_command should respect `path' argument. Looking up in the hash table
> may gives incorrect index in entry.u.index and finally causes incorrect output
> or SIGSEGV.
>
> Signed-off-by: Youfu Zhang <zhangyoufu at gmail.com>
> ---
>  shell/ash.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/shell/ash.c b/shell/ash.c
> index 60c8ffe..1ff9d12 100644
> --- a/shell/ash.c
> +++ b/shell/ash.c
> @@ -8193,15 +8193,8 @@ describe_command(char *command, const char *path, int describe_command_verbose)
>                 goto out;
>         }
>  #endif
> -       /* Then check if it is a tracked alias */
> -       cmdp = cmdlookup(command, 0);
> -       if (cmdp != NULL) {
> -               entry.cmdtype = cmdp->cmdtype;
> -               entry.u = cmdp->param;
> -       } else {
> -               /* Finally use brute force */
> -               find_command(command, &entry, DO_ABS, path);
> -       }
> +       /* Brute force */
> +       find_command(command, &entry, DO_ABS, path);
>
>         switch (entry.cmdtype) {
>         case CMDNORMAL: {

cc1: warnings being treated as errors
shell/ash.c: In function 'describe_command':
shell/ash.c:8212: error: 'cmdp' may be used uninitialized in this function

Applied with a fix.