Re: [PATCH v2] fs: warn in case userspace lied about modprobe return

From: Luis R. Rodriguez
Date: Tue Jun 20 2017 - 16:57:53 EST

On Thu, Jun 01, 2017 at 11:08:01AM -0700, Luis R. Rodriguez wrote:
> kmod <= v19 was broken -- it could return 0 to modprobe calls,
> incorrectly assuming that a kernel module was built-in, whereas in
> reality the module was just forming in the kernel. The reason for this
> is an incorrect userspace heuristics. A userspace kmod fix is available
> for it [0], however should userspace break again we could go on with
> an failed get_fs_type() which is hard to debug as the request_module()
> is detected as returning 0. The first suspect would be that there is
> something worth with the kernel's module loader and obviously in this
> case that is not the issue.
> Since these issues are painful to debug complain when we know userspace
> has outright lied to us.
> [0]
> Suggested-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Jessica Yu <jeyu@xxxxxxxxxx>
> Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>

*poke* Al?