Vulnerability CVE-2024-41062
Published: 2024-07-29

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

bluetooth/l2cap: sync sock recv cb and release

The problem occurs between the system call to close the sock and hci_rx_work,
where the former releases the sock and the latter accesses it without lock protection.

CPU0 CPU1
---- ----
sock_close hci_rx_work
l2cap_sock_release hci_acldata_packet
l2cap_sock_kill l2cap_recv_frame
sk_free l2cap_conless_channel
l2cap_sock_recv_cb

If hci_rx_work processes the data that needs to be received before the sock is
closed, then everything is normal; Otherwise, the work thread may access the
released sock when receiving data.

Add a chan mutex in the rx callback of the sock to achieve synchronization between
the sock release and recv cb.

Sock is dead, so set chan data to NULL, avoid others use invalid sock pointer.

 References:
https://git.kernel.org/stable/c/605572e64cd9cebb05ed609d96cff05b50d18cdf
https://git.kernel.org/stable/c/b803f30ea23e0968b6c8285c42adf0d862ab2bf6
https://git.kernel.org/stable/c/3b732449b78183d17178db40be3a4401cf3cd629
https://git.kernel.org/stable/c/89e856e124f9ae548572c56b1b70c2255705f8fe
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