| Message ID | 18ae685b655c6c9334cb80bb32e6b4a1b423b0ae.1717154083.git.namcao@linutronix.de (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | PCI: of_property: Gracefully handle bridges without secondary bus | expand |
diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c index c2c7334152bc..5fb516807ba2 100644 --- a/drivers/pci/of_property.c +++ b/drivers/pci/of_property.c @@ -91,6 +91,9 @@ static int of_pci_prop_bus_range(struct pci_dev *pdev, struct of_changeset *ocs, struct device_node *np) { + if (!pdev->subordinate) + return 0; + u32 bus_range[] = { pdev->subordinate->busn_res.start, pdev->subordinate->busn_res.end };
The subordinate pointer can be null if we are out of bus number. The function of_pci_prop_bus_range() deferences this pointer without checking and may crashes the kernel. This crash can be reproduced by starting a QEMU instance: qemu-system-riscv64 -machine virt \ -kernel ../build-pci-riscv/arch/riscv/boot/Image \ -append "console=ttyS0 root=/dev/vda" \ -nographic \ -drive "file=root.img,format=raw,id=hd0" \ -device virtio-blk-device,drive=hd0 \ -device pcie-root-port,bus=pcie.0,slot=1,id=rp1,bus-reserve=0 \ -device pcie-pci-bridge,id=br1,bus=rp1 Then hot-add a bridge with device_add pci-bridge,id=br2,bus=br1,chassis_nr=1,addr=1 Then the kernel crashes: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000088 [snip] [<ffffffff804db234>] of_pci_add_properties+0x34c/0x3c6 [<ffffffff804c8228>] of_pci_make_dev_node+0xb6/0x116 [<ffffffff804a6b72>] pci_bus_add_device+0xa8/0xaa [<ffffffff804a6ba4>] pci_bus_add_devices+0x30/0x6a [<ffffffff804d3b5c>] shpchp_configure_device+0xa0/0x112 [<ffffffff804d2b3a>] board_added+0xce/0x354 [<ffffffff804d2e9a>] shpchp_enable_slot+0xda/0x30c [<ffffffff804d336c>] shpchp_pushbutton_thread+0x84/0xa0 NULL check this pointer first before proceeding. Fixes: 407d1a51921e ("PCI: Create device tree node for bridge") Signed-off-by: Nam Cao <namcao@linutronix.de> Cc: stable@vger.kernel.org --- drivers/pci/of_property.c | 3 +++ 1 file changed, 3 insertions(+)