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

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Message-ID: <20170620205746.GY21846@wotan.suse.de>
Date:   Tue, 20 Jun 2017 22:57:46 +0200
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc:     viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, rusty@...tcorp.com.au,
        jeyu@...hat.com
Subject: Re: [PATCH v2] fs: warn in case userspace lied about modprobe return

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] http://git.kernel.org/cgit/utils/kernel/kmod/kmod.git/commit/libkmod/libkmod-module.c?id=fd44a98ae2eb5eb32161088954ab21e58e19dfc4
> 
> Suggested-by: Rusty Russell <rusty@...tcorp.com.au>
> Cc: Jessica Yu <jeyu@...hat.com>
> Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>

*poke* Al?

  Luis