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PCI: Fix pci_slot_release() NULL pointer dereference 

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: 8a94644b44 ("PCI: Fix pci_create_slot() reference count leak")
Link: https://lore.kernel.org/r/1606876422-117457-1-git-send-email-zhongjubin@huawei.com
Signed-off-by: Jubin Zhong <zhongjubin@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org	# v5.9+
This commit is contained in:
Jubin Zhong 2020-12-02 10:33:42 +08:00 committed by Bjorn Helgaas
parent e47756c6b4
commit 4684709bf8
1 changed files with 3 additions and 3 deletions
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6
drivers/pci/slot.c
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@ -272,6 +272,9 @@ placeholder:
goto err; goto err;
} }
INIT_LIST_HEAD(&slot->list);
list_add(&slot->list, &parent->slots);
err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL, err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
"%s", slot_name); "%s", slot_name);
if (err) { if (err) {
@ -279,9 +282,6 @@ placeholder:
goto err; goto err;
} }
INIT_LIST_HEAD(&slot->list);
list_add(&slot->list, &parent->slots);
down_read(&pci_bus_sem); down_read(&pci_bus_sem);
list_for_each_entry(dev, &parent->devices, bus_list) list_for_each_entry(dev, &parent->devices, bus_list)
if (PCI_SLOT(dev->devfn) == slot_nr) if (PCI_SLOT(dev->devfn) == slot_nr)