Re: [PATCH] ksys_mount: check for permissions before resource allocation

Ilya Matveychikov
2018-06-05T11:36:01Z

> On Jun 5, 2018, at 3:26 PM, Al Viro <viro@ZenIV.linux.org.uk> wrote:
>>
>>> On Jun 5, 2018, at 6:00 AM, Ilya Matveychikov <matvejchikov@gmail.com> wrote:
>>>
>>> Early check for mount permissions prevents possible allocation of 3
>>> pages from kmalloc() pool by unpriveledged user which can be used for
>>> spraying the kernel heap.
>
> I'm sorry, but there are arseloads of unpriveleged syscalls that do the same,
> starting with read() from procfs files. So what the hell does it buy?

Means that if all do the same shit no reason to fix it? Sounds weird...