linux-kernel - Re: [PATCH] tpm: fix crash in tpm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Wed, 13 Apr 2016 11:04:26 -0600
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:	Peter Huewe <peterhuewe@....de>,
	Marcel Selhorst <tpmdd@...horst.net>,
	"moderated list:TPM DEVICE DRIVER" 
	<tpmdd-devel@...ts.sourceforge.net>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tpm: fix crash in tpm_tis deinitialization

On Wed, Apr 13, 2016 at 09:58:05AM +0300, Jarkko Sakkinen wrote:
> > > It prevents everything including the kernel from issuing a command
> >                          ^^^^^^^^^^^^^^^^^^^^
> > 
> > That lock is not used to exclude kernel access. Read lock is only taken
> > for the user space device in tpm-dev.c.
> 
> My bad. For the in-kernel API it is taken through tpm_find_get().

Right. At this point any thing that can run in-kernel concurrently
with the write exclusion is a kernel bug. Those places will need to
grab the read side of the lock.

Jason