linux-kernel - Re: [PATCH] acpi / apei: fix NULL deref during init

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Message-ID: <20181214202406.GI11710@zn.tnic>
Date:   Fri, 14 Dec 2018 21:24:06 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Thomas Schoebel-Theuer <tst@...oebel-theuer.de>
Cc:     linux-kernel@...r.kernel.org, Laura Abbott <labbott@...hat.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, Tony Luck <tony.luck@...el.com>,
        linux-acpi@...r.kernel.org
Subject: Re: [PATCH] acpi / apei: fix NULL deref during init

On Fri, Dec 14, 2018 at 07:15:14PM +0100, Thomas Schoebel-Theuer wrote:
> Reason is a conditional initialization of variable arch_res, which happens
> only under a specific precondition. When the condition is false, the
> variable remains uninitialized.

Are you talking about the precondition

	if (arch_apei_filter_addr)

?

Because apei_resources_fini() happens under the same condition check and
if arch_apei_filter_addr was false, it should not become true, all of a
sudden. Or?

Or does that function ptr get set in the meantime on your machine? I.e., this
hackery:

#define set_apei_filter() (arch_apei_filter_addr = pci_mmcfg_for_each_region)

being called in pci_mmcfg_early_init()...

?

Hmmm.

-- 
Regards/Gruss,
    Boris.

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