Re: [PATCH] proc: Escape more characters in /proc/mounts output

[Siddhesh Poyarekar]

On 12/15/20 11:40 AM, Al Viro wrote:
> On Tue, Dec 15, 2020 at 09:54:54AM +0530, Siddhesh Poyarekar wrote:
>
> > +	get_user(byte, (const char __user *)data);
> > +
> > +	return byte ? strndup_user(data, PATH_MAX) : NULL;
> >   }
>
> No.  Not to mention anything else, you
> 	* fetch the same data twice
> 	* fail to check the get_user() results

Ahh sorry, I could inline the strndup_user call and put an additional 
check for length == 1 to return NULL.  Would that be acceptable?

The other alternative would be to not touch copy_mount_string and 
instead, check after fetching the string and if it is blank, free it and 
set to NULL.  That seems more expensive though.

Siddhesh