linux-kernel - Re: [PATCH] platform/x86/amd/pmf: fix cleanup in amd_pmf_init_smart

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]

Message-ID: <4a14c0a5-d6f8-4df9-b947-a0d3c3ef02b3@stanley.mountain>
Date: Mon, 10 Mar 2025 17:52:03 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Shyam Sundar S K <Shyam-sundar.S-k@....com>,
	Hans de Goede <hdegoede@...hat.com>,
	Patil Rajesh Reddy <Patil.Reddy@....com>,
	Mario Limonciello <mario.limonciello@....com>,
	platform-driver-x86@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] platform/x86/amd/pmf: fix cleanup in
 amd_pmf_init_smart_pc()

On Mon, Mar 10, 2025 at 02:43:51PM +0200, Ilpo Järvinen wrote:
> On Mon, 10 Mar 2025, Dan Carpenter wrote:
> 
> > There are a couple problems in this code:
> > 
> > First, if amd_pmf_tee_init() fails then the function returns directly
> > instead of cleaning up.  We cannot simply do a "goto error;" because
> > that would lead to a double free.  I have re-written this code to
> > use an unwind ladder to free the allocations.
> 
> Thanks Dan,
> 
> Could you please amend this with the information of what is getting 
> double freed, it took considerable amount of time for me to figure out.
> I assume it's ->fw_shm_pool ?
> 

Yes, that's it.  Sure, I can re-write that.

> > Second, if amd_pmf_start_policy_engine() fails on every iteration though
> > the loop then the code calls amd_pmf_tee_deinit() twice which is also a
> > double free.  Call amd_pmf_tee_deinit() inside the loop for each failed
> > iteration.  Also on that path the error codes are not necessarily
> > negative kernel error codes.  Set the error code to -EINVAL.
> 
> Maybe I should start to consistently reject any attempt to use 
> cleanup/deinit helper functions instead of a proper rollback. It 
> seems a pattern that is very prone to errors like this.

I do not like deinit functions.  They are so hard to review.  But I
detected this bug because of a Smatch warning:

drivers/platform/x86/amd/pmf/tee-if.c:540 amd_pmf_init_smart_pc() warn: missing unwind goto?

regards,
dan carpenter