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a85fb91e3d
syzbot reports a slab use-after-free in hci_conn_hash_flush [1].
After releasing an object using hci_conn_del_sysfs in the
hci_conn_cleanup function, releasing the same object again
using the hci_dev_put and hci_conn_put functions causes a double free.
Here's a simplified flow:
hci_conn_del_sysfs:
hci_dev_put
put_device
kobject_put
kref_put
kobject_release
kobject_cleanup
kfree_const
kfree(name)
hci_dev_put:
...
kfree(name)
hci_conn_put:
put_device
...
kfree(name)
This patch drop the hci_dev_put and hci_conn_put function
call in hci_conn_cleanup function, because the object is
freed in hci_conn_del_sysfs function.
This patch also fixes the refcounting in hci_conn_add_sysfs() and
hci_conn_del_sysfs() to take into account device_add() failures.
This fixes CVE-2023-28464.
Link: https://syzkaller.appspot.com/bug?id=1bb51491ca5df96a5f724899d1dbb87afda61419 [1]
Signed-off-by: ZhengHan Wang <wzhmmmmm@gmail.com>
Co-developed-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
124 lines
2.4 KiB
C
124 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Bluetooth HCI driver model support. */
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#include <linux/module.h>
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#include <net/bluetooth/bluetooth.h>
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#include <net/bluetooth/hci_core.h>
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static const struct class bt_class = {
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.name = "bluetooth",
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};
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static void bt_link_release(struct device *dev)
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{
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struct hci_conn *conn = to_hci_conn(dev);
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kfree(conn);
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}
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static const struct device_type bt_link = {
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.name = "link",
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.release = bt_link_release,
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};
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/*
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* The rfcomm tty device will possibly retain even when conn
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* is down, and sysfs doesn't support move zombie device,
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* so we should move the device before conn device is destroyed.
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*/
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static int __match_tty(struct device *dev, void *data)
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{
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return !strncmp(dev_name(dev), "rfcomm", 6);
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}
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void hci_conn_init_sysfs(struct hci_conn *conn)
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{
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struct hci_dev *hdev = conn->hdev;
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bt_dev_dbg(hdev, "conn %p", conn);
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conn->dev.type = &bt_link;
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conn->dev.class = &bt_class;
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conn->dev.parent = &hdev->dev;
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device_initialize(&conn->dev);
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}
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void hci_conn_add_sysfs(struct hci_conn *conn)
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{
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struct hci_dev *hdev = conn->hdev;
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bt_dev_dbg(hdev, "conn %p", conn);
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if (device_is_registered(&conn->dev))
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return;
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dev_set_name(&conn->dev, "%s:%d", hdev->name, conn->handle);
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if (device_add(&conn->dev) < 0)
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bt_dev_err(hdev, "failed to register connection device");
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}
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void hci_conn_del_sysfs(struct hci_conn *conn)
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{
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struct hci_dev *hdev = conn->hdev;
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bt_dev_dbg(hdev, "conn %p", conn);
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if (!device_is_registered(&conn->dev)) {
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/* If device_add() has *not* succeeded, use *only* put_device()
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* to drop the reference count.
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*/
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put_device(&conn->dev);
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return;
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}
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while (1) {
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struct device *dev;
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dev = device_find_child(&conn->dev, NULL, __match_tty);
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if (!dev)
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break;
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device_move(dev, NULL, DPM_ORDER_DEV_LAST);
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put_device(dev);
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}
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device_unregister(&conn->dev);
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}
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static void bt_host_release(struct device *dev)
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{
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struct hci_dev *hdev = to_hci_dev(dev);
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if (hci_dev_test_flag(hdev, HCI_UNREGISTER))
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hci_release_dev(hdev);
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else
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kfree(hdev);
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module_put(THIS_MODULE);
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}
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static const struct device_type bt_host = {
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.name = "host",
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.release = bt_host_release,
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};
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void hci_init_sysfs(struct hci_dev *hdev)
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{
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struct device *dev = &hdev->dev;
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dev->type = &bt_host;
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dev->class = &bt_class;
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__module_get(THIS_MODULE);
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device_initialize(dev);
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}
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int __init bt_sysfs_init(void)
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{
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return class_register(&bt_class);
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}
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void bt_sysfs_cleanup(void)
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{
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class_unregister(&bt_class);
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}
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