linux-kernel - Re: [PATCH] irqdomain/treewide: Free firmware node after domain removal

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Message-ID: <87h7tzz1yb.fsf@nanos.tec.linutronix.de>
Date:   Wed, 22 Jul 2020 23:15:08 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Jon Derrick <jonathan.derrick@...el.com>
Cc:     Marc Zyngier <maz@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...el.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <helgaas@...nel.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] irqdomain/treewide: Free firmware node after domain removal

Jon Derrick <jonathan.derrick@...el.com> writes:
> Change 711419e504eb ("irqdomain: Add the missing assignment of
> domain->fwnode for named fwnode") unintentionally caused a dangling
> pointer page fault issue on firmware nodes that were freed after IRQ
> domain allocation. Change e3beca48a45b fixed that dangling pointer issue
> by only freeing the firmware node after an IRQ domain allocation
> failure. That fix no longer frees the firmware node immediately, but
> leaves the firmware node allocated after the domain is removed.

Gah, I missed that under the assumption that these nodes are freed when
the domain is removed. What a mess.

> We need to keep the firmware node through irq_domain_remove, but should
> free it afterwards. This patch saves the handle and adds the freeing of
> firmware node after domain removal where appropriate.

Care to read Documentation/process/submitting-patches.rst and look for
'I/We' and 'This patch' next time?

Thanks,

        tglx