RE: [PATCH 1/2] hexagon/traps.c: use KSYM_NAME_LEN in array size

[David Laight]

From: Maninder Singh
> Sent: 29 May 2023 12:14
> 
> kallsyms_lookup which in turn calls for kallsyms_lookup_buildid()
> writes on index "KSYM_NAME_LEN - 1".
> 
> Thus array size should be KSYM_NAME_LEN.
> 
> for hexagon it was defined as "128" directly.
> and commit '61968dbc2d5d' changed define value to 512,
> So both were missed to update with new size.

The only safe way to pass a fixed size string is to embed the char[] in
a structure and pass the structure address.

Pretty much anything else is doomed to be buggy.

Whether is it actually sane to require the caller allocate
such a large buffer (hi rust) is another matter entirely.

	David

> 
> Fixes: 61968dbc2d5d ("kallsyms: increase maximum kernel symbol length to 512")
> 
> Co-developed-by: Onkarnath <onkarnath.1@xxxxxxxxxxx>
> Signed-off-by: Onkarnath <onkarnath.1@xxxxxxxxxxx>
> Signed-off-by: Maninder Singh <maninder1.s@xxxxxxxxxxx>
> ---
>  arch/hexagon/kernel/traps.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/hexagon/kernel/traps.c b/arch/hexagon/kernel/traps.c
> index 6447763ce5a9..65b30b6ea226 100644
> --- a/arch/hexagon/kernel/traps.c
> +++ b/arch/hexagon/kernel/traps.c
> @@ -82,7 +82,7 @@ static void do_show_stack(struct task_struct *task, unsigned long *fp,
>  	const char *name = NULL;
>  	unsigned long *newfp;
>  	unsigned long low, high;
> -	char tmpstr[128];
> +	char tmpstr[KSYM_NAME_LEN];
>  	char *modname;
>  	int i;
> 
> --
> 2.17.1

-
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