[Crash-utility] [PATCH] Fixed the segment fault when ikconfig passed nonstandard values

[HAGIO KAZUHITO(萩尾 一仁)]

-----Original Message-----
> From: Jackie Liu <liuyun01 at kylinos.cn>
> 
> Some strange reasons may cause kcore to collect some strange
> entries of ikconfig, such as CONFIG_SECU+[some hex data] causes
> the 'val' to be NULL, and then crashes when strdup.
> 
> Signed-off-by: Jackie Liu <liuyun01 at kylinos.cn>
> ---
>  kernel.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel.c b/kernel.c
> index 9871637..aa86f0d 100644
> --- a/kernel.c
> +++ b/kernel.c
> @@ -10244,6 +10244,9 @@ static void add_ikconfig_entry(char *line, struct ikconfig_list *ent)
>  	sscanf(name, "CONFIG_%s", name);
>  	val = strtok_r(NULL, "", &tokptr);
> 
> +	if (!val)
> +		return;
> +

This looks harmless, but kt->ikconfig_ents is incremented unconditionally
in setup_ikconfig() and inconsistent with the following debug message

                        if (setup_ikconfig(pos)) {
                                kt->ikconfig_flags |= IKCONFIG_LOADED;
                                if (CRASHDEBUG(1))
                                        fprintf(fp,
                                        "ikconfig: %d valid configs.\n",
                                                kt->ikconfig_ents);

and it consumes an element of the ikconfig_all array needlessly, so
how about something like this?:

  if (!val) {
    if (CRASHDEBUG(2))
       error(WARNING, "invalid ikconfig entry: %s\n", line);
    return FALSE;
  }
  ...
  return TRUE;

and in setup_ikconfig():

  if (add_ikconfig_entry(ent, &ikconfig_all[kt->ikconfig_ents])
      kt->ikconfig_ents++;

Thanks,
Kazu

>  	ent->name = strdup(name);
>  	ent->val = strdup(val);
>  }
> --
> 2.17.1
> 
> 
> 
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