Re: [PATCH] PCI/MSI: fix page fault when msi_populate_sysfs() failed

["wanghai (M)" <wanghai38@xxxxxxxxxx>]

在 2021/10/11 16:52, Barry Song 写道:
> On Mon, Oct 11, 2021 at 9:24 PM Wang Hai <wanghai38@xxxxxxxxxx> 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@xxxxxxxxxx>
> > Signed-off-by: Wang Hai <wanghai38@xxxxxxxxxx>
> Acked-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx>
>
> > ---
> >   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