Messages in this thread | | | Date | Tue, 11 May 2021 09:03:34 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge |
| |
On Mon, May 10, 2021 at 03:20:02PM -0700, Tong Zhang wrote: > On Mon, May 10, 2021 at 7:36 AM Greg Kroah-Hartman > <gregkh@linuxfoundation.org> wrote: > > > > On Mon, Apr 26, 2021 at 06:07:27PM -0400, Tong Zhang wrote: > > > the PCI bridge might be NULL, so we'd better check before use it > > > > > > [ 1.246492] BUG: kernel NULL pointer dereference, address: 00000000000000c0 > > > [ 1.248731] RIP: 0010:pci_read_config_byte+0x5/0x40 > > > [ 1.253998] Call Trace: > > > [ 1.254131] ? alcor_pci_find_cap_offset.isra.0+0x3a/0x100 [alcor_pci] > > > [ 1.254476] alcor_pci_probe+0x169/0x2d5 [alcor_pci] > > > > > > Signed-off-by: Tong Zhang <ztong0001@gmail.com> > > > --- > > > drivers/misc/cardreader/alcor_pci.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/drivers/misc/cardreader/alcor_pci.c b/drivers/misc/cardreader/alcor_pci.c > > > index cd402c89189e..1c33453fd5c7 100644 > > > --- a/drivers/misc/cardreader/alcor_pci.c > > > +++ b/drivers/misc/cardreader/alcor_pci.c > > > @@ -102,6 +102,9 @@ static int alcor_pci_find_cap_offset(struct alcor_pci_priv *priv, > > > u8 val8; > > > u32 val32; > > > > > > + if (!pci) > > > + return 0; > > > + > > > where = ALCOR_CAP_START_OFFSET; > > > pci_read_config_byte(pci, where, &val8); > > > if (!val8) > > > -- > > > 2.25.1 > > > > > > > I do not understand, how can pci ever be NULL? There is only 1 way this > > Hi Greg, > I think the problem is with > priv->parent_pdev = pdev->bus->self > where bus->self can be NULL. when bus->self is NULL, calling
How can bus->self be NULL?
Did you see this on a real system? How did you duplicate the error listed here?
thanks,
greg k-h
| |