CVE-2024-26886

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

Bluetooth: af_bluetooth: Fix deadlock

Attemting to do sock_lock on .recvmsg may cause a deadlock as shown bellow, so instead of using sock_sock this uses sk_receive_queue.lock on bt_sock_ioctl to avoid the UAF:

INFO: task kworker/u9:1:121 blocked for more than 30 seconds. Not tainted 6.7.6-lemon #183 Workqueue: hci0 hci_rx_work Call Trace: __schedule+0x37d/0xa00 schedule+0x32/0xe0 __lock_sock+0x68/0xa0 ? __pfx_autoremove_wake_function+0x10/0x10 lock_sock_nested+0x43/0x50 l2cap_sock_recv_cb+0x21/0xa0 l2cap_recv_frame+0x55b/0x30a0 ? psi_task_switch+0xeb/0x270 ? finish_task_switch.isra.0+0x93/0x2a0 hci_rx_work+0x33a/0x3f0 process_one_work+0x13a/0x2f0 worker_thread+0x2f0/0x410 ? __pfx_worker_thread+0x10/0x10 kthread+0xe0/0x110 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2c/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30

Weakness

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software

Extended Description

The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:

In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

References

• https://git.kernel.org/stable/c/2c9e2df022ef8b9d7fac58a04a2ef4ed25288955
• https://git.kernel.org/stable/c/64be3c6154886200708da0dfe259705fb992416c
• https://git.kernel.org/stable/c/817e8138ce86001b2fa5c63d6ede756e205a01f7
• https://git.kernel.org/stable/c/f7b94bdc1ec107c92262716b073b3e816d4784fb
• https://git.kernel.org/stable/c/2c9e2df022ef8b9d7fac58a04a2ef4ed25288955
• https://git.kernel.org/stable/c/64be3c6154886200708da0dfe259705fb992416c
• https://git.kernel.org/stable/c/817e8138ce86001b2fa5c63d6ede756e205a01f7
• https://git.kernel.org/stable/c/cb8adca52f306563d958a863bb0cbae9c184d1ae
• https://git.kernel.org/stable/c/f7b94bdc1ec107c92262716b073b3e816d4784fb