Vulnerability CVE-2023-52830
Published: 2024-05-21

Description:
In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: Fix double free in hci_conn_cleanup

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.

 References:
https://git.kernel.org/stable/c/5c53afc766e07098429520b7677eaa164b593451
https://git.kernel.org/stable/c/3c4236f1b2a715e878a06599fa8b0cc21f165d28
https://git.kernel.org/stable/c/53d61daf35b1bbf3ae06e852ee107aa2f05b3776
https://git.kernel.org/stable/c/ba7088769800d9892a7e4f35c3137a5b3e65410b
https://git.kernel.org/stable/c/87624b1f9b781549e69f92db7ede012a21cec275
https://git.kernel.org/stable/c/fc666d1b47518a18519241cae213de1babd4a4ba
https://git.kernel.org/stable/c/56a4fdde95ed98d864611155f6728983e199e198
https://git.kernel.org/stable/c/a85fb91e3d728bdfc80833167e8162cce8bc7004
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