Re: [Linux-kernel-mentees] [PATCH] fs: fix KMSAN uninit-value bug by initializing nd in do_file_open_root

From: Anant Thazhemadam
Date: Sat Sep 19 2020 - 16:17:55 EST

On 19-09-2020 17:03, Anant Thazhemadam wrote:
> On 19-09-2020 22:25, Al Viro wrote:
>> On Sat, Sep 19, 2020 at 05:17:27PM +0100, Al Viro wrote:
>>> Lovely... That would get an empty path and non-directory for a starting
>>> point, but it should end up with LAST_ROOT in nd->last_type. Which should
>>> not be able to reach the readers of those fields... Which kernel had
>>> that been on?
>> Yecchhh... I see what's going on; I suspect that this ought to be enough.
>> Folks, could somebody test it on the original reproducer setup?
> Sure. I can do that.

Looks like this patch actually fixes this bug.
I made syzbot test the patch, and no issues were triggered!

Note:    syzbot tested the patch with the KMSAN kernel, which
was recently rebased on v5.9-rc4.