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

Bluetooth: btrtl: fix out of bounds memory access

The problem is detected by KASAN. btrtl driver uses private hci data to store struct btrealtek_data. If btrtl driver is used with btusb, then memory for private hci data is allocated in btusb. But no private data is allocated after hci_dev, when btrtl is used with hci_h5.

This commit adds memory allocation for hci_h5 case.

================================================================== BUG: KASAN: slab-out-of-bounds in btrtl_initialize+0x6cc/0x958 [btrtl] Write of size 8 at addr ffff00000f5a5748 by task kworker/u9:0/76

Hardware name: Pine64 PinePhone (1.2) (DT) Workqueue: hci0 hci_power_on [bluetooth] Call trace: dump_backtrace+0x9c/0x128 show_stack+0x20/0x38 dump_stack_lvl+0x48/0x60 print_report+0xf8/0x5d8 kasan_report+0x90/0xd0 __asan_store8+0x9c/0xc0 [btrtl] h5_btrtl_setup+0xd0/0x2f8 [hci_uart] h5_setup+0x50/0x80 [hci_uart] hci_uart_setup+0xd4/0x260 [hci_uart] hci_dev_open_sync+0x1cc/0xf68 [bluetooth] hci_dev_do_open+0x34/0x90 [bluetooth] hci_power_on+0xc4/0x3c8 [bluetooth] process_one_work+0x328/0x6f0 worker_thread+0x410/0x778 kthread+0x168/0x178 ret_from_fork+0x10/0x20

Allocated by task 53: kasan_save_stack+0x3c/0x68 kasan_save_track+0x20/0x40 kasan_save_alloc_info+0x68/0x78 __kasan_kmalloc+0xd4/0xd8 __kmalloc+0x1b4/0x3b0 hci_alloc_dev_priv+0x28/0xa58 [bluetooth] hci_uart_register_device+0x118/0x4f8 [hci_uart] h5_serdev_probe+0xf4/0x178 [hci_uart] serdev_drv_probe+0x54/0xa0 really_probe+0x254/0x588 __driver_probe_device+0xc4/0x210 driver_probe_device+0x64/0x160 __driver_attach_async_helper+0x88/0x158 async_run_entry_fn+0xd0/0x388 process_one_work+0x328/0x6f0 worker_thread+0x410/0x778 kthread+0x168/0x178 ret_from_fork+0x10/0x20

Last potentially related work creation: kasan_save_stack+0x3c/0x68 __kasan_record_aux_stack+0xb0/0x150 kasan_record_aux_stack_noalloc+0x14/0x20 __queue_work+0x33c/0x960 queue_work_on+0x98/0xc0 hci_recv_frame+0xc8/0x1e8 [bluetooth] h5_complete_rx_pkt+0x2c8/0x800 [hci_uart] h5_rx_payload+0x98/0xb8 [hci_uart] h5_recv+0x158/0x3d8 [hci_uart] hci_uart_receive_buf+0xa0/0xe8 [hci_uart] ttyport_receive_buf+0xac/0x178 flush_to_ldisc+0x130/0x2c8 process_one_work+0x328/0x6f0 worker_thread+0x410/0x778 kthread+0x168/0x178 ret_from_fork+0x10/0x20

Second to last potentially related work creation: kasan_save_stack+0x3c/0x68 __kasan_record_aux_stack+0xb0/0x150 kasan_record_aux_stack_noalloc+0x14/0x20 __queue_work+0x788/0x960 queue_work_on+0x98/0xc0 __hci_cmd_sync_sk+0x23c/0x7a0 [bluetooth] __hci_cmd_sync+0x24/0x38 [bluetooth] btrtl_initialize+0x760/0x958 [btrtl] h5_btrtl_setup+0xd0/0x2f8 [hci_uart] h5_setup+0x50/0x80 [hci_uart] hci_uart_setup+0xd4/0x260 [hci_uart] hci_dev_open_sync+0x1cc/0xf68 [bluetooth] hci_dev_do_open+0x34/0x90 [bluetooth] hci_power_on+0xc4/0x3c8 [bluetooth] process_one_work+0x328/0x6f0 worker_thread+0x410/0x778 kthread+0x168/0x178 ret_from_fork+0x10/0x20

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/0c657e641df1e77d6087688190f632cad9c0439b
• https://git.kernel.org/stable/c/2f232bc389a4f5943c40733582f9edf77b89e499
• https://git.kernel.org/stable/c/dd163fa34c483f1674aa2510accce11a224f649e
• https://git.kernel.org/stable/c/de4e88ec58c4202efd1f02eebb4939bbf6945358