linux-kernel - Re: [PATCH] PCI/MSI: fix page fault when msi_populate

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Date:   Mon, 11 Oct 2021 21:09:59 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     "wanghai (M)" <wanghai38@...wei.com>
Cc:     Barry Song <21cnbao@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Barry Song <song.bao.hua@...ilicon.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-pci@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI/MSI: fix page fault when msi_populate_sysfs() failed

On Tue, Oct 12, 2021 at 09:59:40AM +0800, wanghai (M) wrote:
> 
> 在 2021/10/12 1:11, Bjorn Helgaas 写道:
> > For v2, please note "git log --oneline drivers/pci/msi.c" and make
> > your patch follow the style, including capitalization.
> > 
> > On Mon, Oct 11, 2021 at 05:15:28PM +0800, wanghai (M) wrote:
> > > 在 2021/10/11 16:52, Barry Song 写道:
> > > > On Mon, Oct 11, 2021 at 9:24 PM Wang Hai <wanghai38@...wei.com> wrote:
> > > > > I got a page fault report when doing fault injection test:
> > When you send v2, can you include information about how you injected
> > the fault?  If it's easy, others can reproduce the failure that way.
> Sorry, the reproduction needs to be based on the fault injection framework
> provided by Hulk Robot. I don't know how the framework is implemented.
> 
> The way to reproduce this is to do a fault injection to make
> 'msi_attrs = kcalloc() in msi_populate_sysfs()' fail when insmod
> 9pnet_virtio.ko.
> 
> I sent v2 yesterday, can you help review it?
> https://lore.kernel.org/linux-pci/20211011130837.766323-1-wanghai38@huawei.com/
> > > > > BUG: unable to handle page fault for address: fffffffffffffff4
> > > > > ...
> > > > > RIP: 0010:sysfs_remove_groups+0x25/0x60
> > > > > ...
> > > > > Call Trace:
> > > > >    msi_destroy_sysfs+0x30/0xa0
> > > > >    free_msi_irqs+0x11d/0x1b0
> > > > >    __pci_enable_msix_range+0x67f/0x760
> > > > >    pci_alloc_irq_vectors_affinity+0xe7/0x170
> > > > >    vp_find_vqs_msix+0x129/0x560
> > > > >    vp_find_vqs+0x52/0x230
> > > > >    vp_modern_find_vqs+0x47/0xb0
> > > > >    p9_virtio_probe+0xa1/0x460 [9pnet_virtio]
> > > > >    virtio_dev_probe+0x1ed/0x2e0
> > > > >    really_probe+0x1c7/0x400
> > > > >    __driver_probe_device+0xa4/0x120
> > > > >    driver_probe_device+0x32/0xe0
> > > > >    __driver_attach+0xbf/0x130
> > > > >    bus_for_each_dev+0xbb/0x110
> > > > >    driver_attach+0x27/0x30
> > > > >    bus_add_driver+0x1d9/0x270
> > > > >    driver_register+0xa9/0x180
> > > > >    register_virtio_driver+0x31/0x50
> > > > >    p9_virtio_init+0x3c/0x1000 [9pnet_virtio]
> > > > >    do_one_initcall+0x7b/0x380
> > > > >    do_init_module+0x5f/0x21e
> > > > >    load_module+0x265c/0x2c60
> > > > >    __do_sys_finit_module+0xb0/0xf0
> > > > >    __x64_sys_finit_module+0x1a/0x20
> > > > >    do_syscall_64+0x34/0xb0
> > > > >    entry_SYSCALL_64_after_hwframe+0x44/0xae
> > > > > 
> > > > > When populating msi_irqs sysfs failed in msi_capability_init() or
> > > > > msix_capability_init(), dev->msi_irq_groups will point to ERR_PTR(...).
> > > > > This will cause a page fault when destroying the wrong
> > > > > dev->msi_irq_groups in free_msi_irqs().
> > > > > 
> > > > > Fix this by setting dev->msi_irq_groups to NULL when msi_populate_sysfs()
> > > > > failed.
> > > > > 
> > > > > Fixes: 2f170814bdd2 ("genirq/msi: Move MSI sysfs handling from PCI to MSI core")
> > > > > Reported-by: Hulk Robot <hulkci@...wei.com>
> > What exactly was reported by the Hulk Robot?  Did it really do the
> > fault injection and report the page fault?
> Yes, it reported the error and provided a way to reproduce it

Great, can you include a link to that report then?