linux-kernel - Re: [PATCH] xen/events: avoid using info_for_irq() in xen_send_IPI

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:   Mon, 30 Oct 2023 17:19:36 -0700 (PDT)
From:   Stefano Stabellini <sstabellini@...nel.org>
To:     Juergen Gross <jgross@...e.com>
cc:     linux-kernel@...r.kernel.org,
        Stefano Stabellini <sstabellini@...nel.org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        xen-devel@...ts.xenproject.org, David Woodhouse <dwmw@...zon.co.uk>
Subject: Re: [PATCH] xen/events: avoid using info_for_irq() in
 xen_send_IPI_one()

On Mon, 30 Oct 2023, Juergen Gross wrote:
> xen_send_IPI_one() is being used by cpuhp_report_idle_dead() after
> it calls rcu_report_dead(), meaning that any RCU usage by
> xen_send_IPI_one() is a bad idea.
> 
> Unfortunately xen_send_IPI_one() is using notify_remote_via_irq()
> today, which is using irq_get_chip_data() via info_for_irq(). And
> irq_get_chip_data() in turn is using a maple-tree lookup requiring
> RCU.
> 
> Avoid this problem by caching the ipi event channels in another
> percpu variable, allowing the use notify_remote_via_evtchn() in
> xen_send_IPI_one().
> 
> Fixes: 721255b9826b ("genirq: Use a maple tree for interrupt descriptor management")
> Reported-by: David Woodhouse <dwmw@...zon.co.uk>
> Signed-off-by: Juergen Gross <jgross@...e.com>
> Tested-by: David Woodhouse <dwmw@...zon.co.uk>

Acked-by: Stefano Stabellini <sstabellini@...nel.org>