[Crash-utility] [PATCH v2] Fixed the segment fault when ikconfig passed nonstandard values

[HAGIO KAZUHITO(萩尾 一仁)]

Hi Jackie,

-----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.
> 
> CONFIG_SECU+[some hex data] to be **strings that don't
> contain the delimitor string '='** and then strtok_r() interprets
> it as consisting of a single token, hence val resulting in having NULL.

Thanks for the update, I will modify the commit message a bit more
as follows, I think you use arm64 kernels:
--- 
Fix for a segmentation fault when analyzing arm64 kernels that are
configured with CONFIG_IKCONFIG and have a strange entry that does
not contain the delimiter "=", such as "CONFIG_SECU+[some hex data]".

Without the patch, in the add_ikconfig_entry() function, strtok_r()
interprets it as consisting of a single token and the val variable
is set to NULL, and then strdup() crashes.
---

and
Acked-by: Kazuhito Hagio <k-hagio-ab at nec.com>

Please wait for another ack.

Thanks,
Kazu

> 
> [d.hatayama at fujitsu.com: rewrite comment]
> Suggested-by: HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab at nec.com>
> Signed-off-by: Jackie Liu <liuyun01 at kylinos.cn>
> ---
>  kernel.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel.c b/kernel.c
> index 9871637..c8182a6 100644
> --- a/kernel.c
> +++ b/kernel.c
> @@ -10236,7 +10236,7 @@ static struct ikconfig_list {
>  	char *val;
>  } *ikconfig_all;
> 
> -static void add_ikconfig_entry(char *line, struct ikconfig_list *ent)
> +static int add_ikconfig_entry(char *line, struct ikconfig_list *ent)
>  {
>  	char *tokptr, *name, *val;
> 
> @@ -10244,8 +10244,16 @@ static void add_ikconfig_entry(char *line, struct ikconfig_list *ent)
>  	sscanf(name, "CONFIG_%s", name);
>  	val = strtok_r(NULL, "", &tokptr);
> 
> +	if (!val) {
> +		if (CRASHDEBUG(2))
> +			error(WARNING, "invalid ikconfig entry: %s\n", line);
> +		return FALSE;
> +	}
> +
>  	ent->name = strdup(name);
>  	ent->val = strdup(val);
> +
> +	return TRUE;
>  }
> 
>  static int setup_ikconfig(char *config)
> @@ -10265,8 +10273,8 @@ static int setup_ikconfig(char *config)
>  			ent++;
> 
>  		if (STRNEQ(ent, "CONFIG_")) {
> -			add_ikconfig_entry(ent,
> -					 &ikconfig_all[kt->ikconfig_ents++]);
> +			if (add_ikconfig_entry(ent, &ikconfig_all[kt->ikconfig_ents]))
> +				kt->ikconfig_ents++;
>  			if (kt->ikconfig_ents == IKCONFIG_MAX) {
>  				error(WARNING, "ikconfig overflow.\n");
>  				return 1;
> --
> 2.17.1
> 
>