CVE-2021-47333

In the Linux kernel, the following vulnerability has been resolved: misc:
alcor_pci: fix null-ptr-deref when there is no PCI bridge There is an issue
with the ASPM(optional) capability checking function. A device might be
attached to root complex directly, in this case, bus->self(bridge) will be
NULL, thus priv->parent_pdev is NULL. Since
alcor_pci_init_check_aspm(priv->parent_pdev) checks the PCI link’s ASPM
capability and populate parent_cap_off, which will be used later by
alcor_pci_aspm_ctrl() to dynamically turn on/off device, what we can do
here is to avoid checking the capability if we are on the root complex.
This will make pdev_cap_off 0 and alcor_pci_aspm_ctrl() will simply return
when bring called, effectively disable ASPM for the device. [ 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]