linux-kernel - [PATCH 4.19 346/346] PCI: Fix pci_slot

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20201228124936.486550319@linuxfoundation.org>
Date:   Mon, 28 Dec 2020 13:51:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jubin Zhong <zhongjubin@...wei.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH 4.19 346/346] PCI: Fix pci_slot_release() NULL pointer dereference

From: Jubin Zhong <zhongjubin@...wei.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@huawei.com
Signed-off-by: Jubin Zhong <zhongjubin@...wei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: stable@...r.kernel.org	# v5.9+
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/pci/slot.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/pci/slot.c
+++ b/drivers/pci/slot.c
@@ -307,6 +307,9 @@ 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) {
@@ -314,9 +317,6 @@ 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)