From: Jubin Zhong zhongjubin@huawei.com
commit 4684709bf81a2d98152ed6b610e3d5c403f9bced upstream.
If kobject_init_and_add() fails, pci_slot_release() is called to delete slot->list from parent->slots. But slot->list hasn't been initialized yet, so we dereference a NULL pointer:
Unable to handle kernel NULL pointer dereference at virtual address 00000000 ... CPU: 10 PID: 1 Comm: swapper/0 Not tainted 4.4.240 #197 task: ffffeb398a45ef10 task.stack: ffffeb398a470000 PC is at __list_del_entry_valid+0x5c/0xb0 LR is at pci_slot_release+0x84/0xe4 ... __list_del_entry_valid+0x5c/0xb0 pci_slot_release+0x84/0xe4 kobject_put+0x184/0x1c4 pci_create_slot+0x17c/0x1b4 __pci_hp_initialize+0x68/0xa4 pciehp_probe+0x1a4/0x2fc pcie_port_probe_service+0x58/0x84 driver_probe_device+0x320/0x470
Initialize slot->list before calling kobject_init_and_add() to avoid this.
Fixes: 8a94644b440e ("PCI: Fix pci_create_slot() reference count leak") Link: https://lore.kernel.org/r/1606876422-117457-1-git-send-email-zhongjubin@huaw... Signed-off-by: Jubin Zhong zhongjubin@huawei.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Cc: stable@vger.kernel.org # v5.9+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/pci/slot.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/pci/slot.c +++ b/drivers/pci/slot.c @@ -308,6 +308,9 @@ placeholder: goto err; }
+ INIT_LIST_HEAD(&slot->list); + list_add(&slot->list, &parent->slots); + err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL, "%s", slot_name); if (err) { @@ -315,9 +318,6 @@ placeholder: goto err; }
- INIT_LIST_HEAD(&slot->list); - list_add(&slot->list, &parent->slots); - down_read(&pci_bus_sem); list_for_each_entry(dev, &parent->devices, bus_list) if (PCI_SLOT(dev->devfn) == slot_nr)