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

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Date:   Mon, 11 Oct 2021 17:15:28 +0800
From:   "wanghai (M)" <wanghai38@...wei.com>
To:     Barry Song <21cnbao@...il.com>
CC:     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


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:
>>
>> 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>
>> Signed-off-by: Wang Hai <wanghai38@...wei.com>
> Acked-by: Barry Song <song.bao.hua@...ilicon.com>
>
>> ---
>>   drivers/pci/msi.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
>> index 0099a00af361..6f75db9f3be7 100644
>> --- a/drivers/pci/msi.c
>> +++ b/drivers/pci/msi.c
>> @@ -561,6 +561,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
>>          dev->msi_irq_groups = msi_populate_sysfs(&dev->dev);
>>          if (IS_ERR(dev->msi_irq_groups)) {
>>                  ret = PTR_ERR(dev->msi_irq_groups);
>> +               dev->msi_irq_groups = NULL;
>>                  goto err;
>>          }
>>
>> @@ -733,6 +734,7 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
>>          dev->msi_irq_groups = msi_populate_sysfs(&dev->dev);
>>          if (IS_ERR(dev->msi_irq_groups)) {
>>                  ret = PTR_ERR(dev->msi_irq_groups);
>> +               dev->msi_irq_groups = NULL;
> Can you define a temp variable and assign it to dev->msi_irq_groups if
> the temp variable
> is not PTR_ERR?
Of course, I will send a v2 patch.
>
>>                  goto out_free;
>>          }
>>
>> --
>> 2.17.1
>>
> Thanks
> Barry
> .
>
-- 
Wang Hai