Re: [PATCH] SN2: security hole in sn2_ptc_proc_write

[Andi Kleen <andi@firstfloor.org>]

Cliff Wickman <cpw@sgi.com> writes:
>
> Signed-off-by: Cliff Wickman <cpw@sgi.com>
> ---
>  arch/ia64/sn/kernel/sn2/sn2_smp.c |    2 ++
>  1 file changed, 2 insertions(+)
>
> Index: linux-2.6/arch/ia64/sn/kernel/sn2/sn2_smp.c
> =================================> --- linux-2.6.orig/arch/ia64/sn/kernel/sn2/sn2_smp.c
> +++ linux-2.6/arch/ia64/sn/kernel/sn2/sn2_smp.c
> @@ -512,6 +512,8 @@ static ssize_t sn2_ptc_proc_write(struct
>  	int cpu;
>  	char optstr[64];
>  
> +	if (count > 64)
> +		return -EINVAL;
>  	if (copy_from_user(optstr, user, count))
>  		return -EFAULT;
>  	optstr[count - 1] = '\0';


When someone passes 0 you get an buffer underflow? 

You need if (count < 0 || count > 64) me thinks.

-Andi