Re: [PATCH V3 2/2] Move stack parameters for sed_ioctl to prevent oversized stack with CONFIG_KASAN

[Rafael Antognolli]

On Thu, Feb 09, 2017 at 10:20:01AM -0700, Scott Bauer wrote:
> When CONFIG_KASAN is enabled, compilation fails:
> 
> block/sed-opal.c: In function 'sed_ioctl':
> block/sed-opal.c:2447:1: error: the frame size of 2256 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
> 
> Moved all the ioctl structures off the stack and dynamically activate
> using _IOC_SIZE()

I just went through the other threads about this issue. This approach
looks good to me.

Rafael

> Fixes: 455a7b238cd6 ("block: Add Sed-opal library")
> 
> Reported-by: Arnd Bergmann <arnd@xxxxxxxx>
> Signed-off-by: Scott Bauer <scott.bauer@xxxxxxxxx>
> ---
>  block/sed-opal.c | 134 +++++++++++++++++++++----------------------------------
>  1 file changed, 50 insertions(+), 84 deletions(-)
> 
> diff --git a/block/sed-opal.c b/block/sed-opal.c
> index bf1406e..4985d95 100644
> --- a/block/sed-opal.c
> +++ b/block/sed-opal.c
> @@ -2346,7 +2346,10 @@ EXPORT_SYMBOL(opal_unlock_from_suspend);
>  
>  int sed_ioctl(struct opal_dev *dev, unsigned int cmd, unsigned long ptr)
>  {
> +	void *ioctl_ptr;
> +	int ret = -ENOTTY;
>  	void __user *arg = (void __user *)ptr;
> +	unsigned int cmd_size = _IOC_SIZE(cmd);
>  
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EACCES;
> @@ -2355,94 +2358,57 @@ int sed_ioctl(struct opal_dev *dev, unsigned int cmd, unsigned long ptr)
>  		return -ENOTSUPP;
>  	}
>  
> -	switch (cmd) {
> -	case IOC_OPAL_SAVE: {
> -		struct opal_lock_unlock lk_unlk;
> -
> -		if (copy_from_user(&lk_unlk, arg, sizeof(lk_unlk)))
> -			return -EFAULT;
> -		return opal_save(dev, &lk_unlk);
> -	}
> -	case IOC_OPAL_LOCK_UNLOCK: {
> -		struct opal_lock_unlock lk_unlk;
> -
> -		if (copy_from_user(&lk_unlk, arg, sizeof(lk_unlk)))
> -			return -EFAULT;
> -		return opal_lock_unlock(dev, &lk_unlk);
> -	}
> -	case IOC_OPAL_TAKE_OWNERSHIP: {
> -		struct opal_key opal_key;
> -
> -		if (copy_from_user(&opal_key, arg, sizeof(opal_key)))
> -			return -EFAULT;
> -		return opal_take_ownership(dev, &opal_key);
> -	}
> -	case IOC_OPAL_ACTIVATE_LSP: {
> -		struct opal_lr_act opal_lr_act;
> -
> -		if (copy_from_user(&opal_lr_act, arg, sizeof(opal_lr_act)))
> -			return -EFAULT;
> -		return opal_activate_lsp(dev, &opal_lr_act);
> -	}
> -	case IOC_OPAL_SET_PW: {
> -		struct opal_new_pw opal_pw;
> -
> -		if (copy_from_user(&opal_pw, arg, sizeof(opal_pw)))
> -			return -EFAULT;
> -		return opal_set_new_pw(dev, &opal_pw);
> -	}
> -	case IOC_OPAL_ACTIVATE_USR: {
> -		struct opal_session_info session;
> -
> -		if (copy_from_user(&session, arg, sizeof(session)))
> -			return -EFAULT;
> -		return opal_activate_user(dev, &session);
> -	}
> -	case IOC_OPAL_REVERT_TPR: {
> -		struct opal_key opal_key;
> -
> -		if (copy_from_user(&opal_key, arg, sizeof(opal_key)))
> -			return -EFAULT;
> -		return opal_reverttper(dev, &opal_key);
> -	}
> -	case IOC_OPAL_LR_SETUP: {
> -		struct opal_user_lr_setup lrs;
> -
> -		if (copy_from_user(&lrs, arg, sizeof(lrs)))
> -			return -EFAULT;
> -		return opal_setup_locking_range(dev, &lrs);
> -	}
> -	case IOC_OPAL_ADD_USR_TO_LR: {
> -		struct opal_lock_unlock lk_unlk;
> -
> -		if (copy_from_user(&lk_unlk, arg, sizeof(lk_unlk)))
> -			return -EFAULT;
> -		return opal_add_user_to_lr(dev, &lk_unlk);
> -	}
> -	case IOC_OPAL_ENABLE_DISABLE_MBR: {
> -		struct opal_mbr_data mbr;
> -
> -		if (copy_from_user(&mbr, arg, sizeof(mbr)))
> -			return -EFAULT;
> -		return opal_enable_disable_shadow_mbr(dev, &mbr);
> -	}
> -	case IOC_OPAL_ERASE_LR: {
> -		struct opal_session_info session;
> -
> -		if (copy_from_user(&session, arg, sizeof(session)))
> -			return -EFAULT;
> -		return opal_erase_locking_range(dev, &session);
> +	ioctl_ptr = kzalloc(cmd_size, GFP_KERNEL);
> +	if (!ioctl_ptr)
> +		return -ENOMEM;
> +	if (copy_from_user(ioctl_ptr, arg, cmd_size)) {
> +		ret = -EFAULT;
> +		goto out;
>  	}
> -	case IOC_OPAL_SECURE_ERASE_LR: {
> -		struct opal_session_info session;
>  
> -		if (copy_from_user(&session, arg, sizeof(session)))
> -			return -EFAULT;
> -		return opal_secure_erase_locking_range(dev, &session);
> -	}
> +	switch (cmd) {
> +	case IOC_OPAL_SAVE:
> +		ret = opal_save(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_LOCK_UNLOCK:
> +		ret = opal_lock_unlock(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_TAKE_OWNERSHIP:
> +		ret = opal_take_ownership(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_ACTIVATE_LSP:
> +		ret = opal_activate_lsp(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_SET_PW:
> +		ret = opal_set_new_pw(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_ACTIVATE_USR:
> +		ret = opal_activate_user(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_REVERT_TPR:
> +		ret = opal_reverttper(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_LR_SETUP:
> +		ret = opal_setup_locking_range(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_ADD_USR_TO_LR:
> +		ret = opal_add_user_to_lr(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_ENABLE_DISABLE_MBR:
> +		ret = opal_enable_disable_shadow_mbr(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_ERASE_LR:
> +		ret = opal_erase_locking_range(dev, ioctl_ptr);
> +		break;
> +	case IOC_OPAL_SECURE_ERASE_LR:
> +		ret = opal_secure_erase_locking_range(dev, ioctl_ptr);
> +		break;
>  	default:
>  		pr_warn("No such Opal Ioctl %u\n", cmd);
>  	}
> -	return -ENOTTY;
> +
> +out:
> +	kfree(ioctl_ptr);
> +	return ret;
>  }
>  EXPORT_SYMBOL_GPL(sed_ioctl);
> -- 
> 2.7.4
> 
> 
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