Re: [uml-devel] [patch] uml: check length in exitcode_proc_write()

[Richard Weinberger <richard@nod.at>]

Am 29.10.2013 20:06, schrieb Dan Carpenter:
> We don't cap the size of buffer from the user so we could write past
> the end of the array here.  Only root can write to this file.
> 
> Reported-by: Nico Golde <nico@ngolde.de>
> Reported-by: Fabian Yamaguchi <fabs@goesec.de>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Thanks everyone!
Patch applied and an it's way to Linus' tree.

Thanks,
//richard

> diff --git a/arch/um/kernel/exitcode.c b/arch/um/kernel/exitcode.c
> index 829df49..41ebbfe 100644
> --- a/arch/um/kernel/exitcode.c
> +++ b/arch/um/kernel/exitcode.c
> @@ -40,9 +40,11 @@ static ssize_t exitcode_proc_write(struct file *file,
>  		const char __user *buffer, size_t count, loff_t *pos)
>  {
>  	char *end, buf[sizeof("nnnnn\0")];
> +	size_t size;
>  	int tmp;
>  
> -	if (copy_from_user(buf, buffer, count))
> +	size = min(count, sizeof(buf));
> +	if (copy_from_user(buf, buffer, size))
>  		return -EFAULT;
>  
>  	tmp = simple_strtol(buf, &end, 0);
> 


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