kernel/linux.git/drivers/bluetooth/hci_ldisc.c, branch linux-7.1.y

Bluetooth: hci_uart: fix UAFs and race conditions in close and init paths

2026-05-20T20:35:47+00:00

Vulnerabilities leading to Use-After-Free (UAF) and Null Pointer Dereference (NPD) conditions were observed in the lifecycle management of hci_uart. The primary issue arises because the workqueues (init_ready and write_work) are only flushed/cancelled if the HCI_UART_PROTO_READY flag is set during TTY close. If a hangup occurs before setup completes, hci_uart_tty_close() skips the teardown of these workqueues and proceeds to free the `hu` struct. When the scheduled work executes later, it blindly dereferences the freed `hu` struct. Furthermore, several data races and UAFs were identified in the teardown sequence: 1. Calling hci_uart_flush() from hci_uart_close() without effectively disabling write_work causes a race condition where both can concurrently double-free hu->tx_skb. This happens because protocol timers can concurrently invoke hci_uart_tx_wakeup() and requeue write_work. 2. Calling hci_free_dev(hdev) before hu->proto->close(hu) causes a UAF when vendor specific protocol close callbacks dereference hu->hdev. 3. In the initialization error paths, failing to take the proto_lock write lock before clearing PROTO_READY leads to races with active readers. Additionally, hci_uart_tty_receive() accesses hu->hdev outside the read lock, leading to UAFs if the initialization error path frees hdev concurrently. Fix these synchronization and lifecycle issues by: 1. Re-ordering hci_uart_tty_close() to clear HCI_UART_PROTO_READY first, followed immediately by a cancel_work_sync(&hu->write_work). Clearing the flag locks out concurrent protocol timers from successfully invoking hci_uart_tx_wakeup(), effectively rendering the cancellation permanent and preventing the tx_skb double-free. 2. Note: Clearing PROTO_READY early causes hci_uart_close() to skip hu->proto->flush(). This is perfectly safe in the tty_close path because hu->proto->close() executes shortly after, which intrinsically purges all protocol SKB queues and tears down the state. 3. Relocating hu->proto->close(hu) strictly prior to hci_free_dev(hdev) across all close and error paths to prevent vendor-level UAFs. 4. Moving the hdev->stat.byte_rx increment in hci_uart_tty_receive() inside the proto_lock read-side critical section to safely synchronize with device unregistration. 5. Adding cancel_work_sync(&hu->write_work) to hci_uart_close() to safely flush the workqueue before hci_uart_flush() is invoked via the HCI core. 6. Utilizing cancel_work_sync() instead of disable_work_sync() across all paths to prevent permanently breaking user-space retry capabilities. Fixes: 3b799254cf6f ("Bluetooth: hci_uart: Cancel init work before unregistering") Cc: stable@vger.kernel.org Signed-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn> Signed-off-by: Luiz Augusto von Dentz

Bluetooth: hci_ldisc: Clear HCI_UART_PROTO_INIT on error

2026-04-13T13:18:16+00:00

When hci_register_dev() fails in hci_uart_register_dev() HCI_UART_PROTO_INIT is not cleared before calling hu->proto->close(hu) and setting hu->hdev to NULL. This means incoming UART data will reach the protocol-specific recv handler in hci_uart_tty_receive() after resources are freed. Clear HCI_UART_PROTO_INIT with a write lock before calling hu->proto->close() and setting hu->hdev to NULL. The write lock ensures all active readers have completed and no new reader can enter the protocol recv path before resources are freed. This allows the protocol-specific recv functions to remove the "HCI_UART_REGISTERED" guard without risking a null pointer dereference if hci_register_dev() fails. Fixes: 5df5dafc171b ("Bluetooth: hci_uart: Fix another race during initialization") Signed-off-by: Jonathan Rissanen Signed-off-by: Luiz Augusto von Dentz

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

Bluetooth: hci_uart: fix null-ptr-deref in hci_uart_write_work

2026-01-22T18:22:22+00:00

hci_uart_set_proto() sets HCI_UART_PROTO_INIT before calling hci_uart_register_dev(), which calls proto->open() to initialize hu->priv. However, if a TTY write wakeup occurs during this window, hci_uart_tx_wakeup() may schedule write_work before hu->priv is initialized, leading to a NULL pointer dereference in hci_uart_write_work() when proto->dequeue() accesses hu->priv. The race condition is: CPU0 CPU1 ---- ---- hci_uart_set_proto() set_bit(HCI_UART_PROTO_INIT) hci_uart_register_dev() tty write wakeup hci_uart_tty_wakeup() hci_uart_tx_wakeup() schedule_work(&hu->write_work) proto->open(hu) // initializes hu->priv hci_uart_write_work() hci_uart_dequeue() proto->dequeue(hu) // accesses hu->priv (NULL!) Fix this by moving set_bit(HCI_UART_PROTO_INIT) after proto->open() succeeds, ensuring hu->priv is initialized before any work can be scheduled. Fixes: 5df5dafc171b ("Bluetooth: hci_uart: Fix another race during initialization") Link: https://lore.kernel.org/linux-bluetooth/6969764f.170a0220.2b9fc4.35a7@mx.google.com/ Signed-off-by: Jia-Hong Su Signed-off-by: Luiz Augusto von Dentz

Bluetooth: hci_dev: replace 'quirks' integer by 'quirk_flags' bitmap

2025-07-16T19:37:53+00:00

The 'quirks' member already ran out of bits on some platforms some time ago. Replace the integer member by a bitmap in order to have enough bits in future. Replace raw bit operations by accessor macros. Fixes: ff26b2dd6568 ("Bluetooth: Add quirk for broken READ_VOICE_SETTING") Fixes: 127881334eaa ("Bluetooth: Add quirk for broken READ_PAGE_SCAN_TYPE") Suggested-by: Pauli Virtanen Tested-by: Ivan Pravdin Signed-off-by: Kiran K Signed-off-by: Christian Eggers Signed-off-by: Luiz Augusto von Dentz

Bluetooth: hci_uart: Fix another race during initialization

2025-03-25T16:32:15+00:00

Do not set 'HCI_UART_PROTO_READY' before call 'hci_uart_register_dev()'. Possible race is when someone calls 'hci_tty_uart_close()' after this bit is set, but 'hci_uart_register_dev()' wasn't done. This leads to access to uninitialized fields. To fix it let's set this bit after device was registered (as before patch c411c62cc133) and to fix previous problem let's add one more bit in addition to 'HCI_UART_PROTO_READY' which allows to perform power up without original bit set (pls see commit c411c62cc133). Crash backtrace from syzbot report: RIP: 0010:skb_queue_empty_lockless include/linux/skbuff.h:1887 [inline] RIP: 0010:skb_queue_purge_reason+0x6d/0x140 net/core/skbuff.c:3936 Call Trace: skb_queue_purge include/linux/skbuff.h:3364 [inline] mrvl_close+0x2f/0x90 drivers/bluetooth/hci_mrvl.c:100 hci_uart_tty_close+0xb6/0x120 drivers/bluetooth/hci_ldisc.c:557 tty_ldisc_close drivers/tty/tty_ldisc.c:455 [inline] tty_ldisc_kill+0x66/0xc0 drivers/tty/tty_ldisc.c:613 tty_ldisc_release+0xc9/0x120 drivers/tty/tty_ldisc.c:781 tty_release_struct+0x10/0x80 drivers/tty/tty_io.c:1690 tty_release+0x4ef/0x640 drivers/tty/tty_io.c:1861 __fput+0x86/0x2a0 fs/file_table.c:450 task_work_run+0x82/0xb0 kernel/task_work.c:239 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0xa3/0x1b0 kernel/entry/common.c:218 do_syscall_64+0x9a/0x190 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f Signed-off-by: Arseniy Krasnov Reported-by: syzbot+683f8cb11b94b1824c77@syzkaller.appspotmail.com Tested-by: syzbot+683f8cb11b94b1824c77@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-bluetooth/d159c57f-8490-4c26-79da-6ad3612c4a14@salutedevices.com/ Fixes: 366ceff495f9 ("Bluetooth: hci_uart: fix race during initialization") Signed-off-by: Luiz Augusto von Dentz

Bluetooth: hci_uart: fix race during initialization

2025-03-25T16:31:59+00:00

'hci_register_dev()' calls power up function, which is executed by kworker - 'hci_power_on()'. This function does access to bluetooth chip using callbacks from 'hci_ldisc.c', for example 'hci_uart_send_frame()'. Now 'hci_uart_send_frame()' checks 'HCI_UART_PROTO_READY' bit set, and if not - it fails. Problem is that 'HCI_UART_PROTO_READY' is set after 'hci_register_dev()', and there is tiny chance that 'hci_power_on()' will be executed before setting this bit. In that case HCI init logic fails. Patch moves setting of 'HCI_UART_PROTO_READY' before calling function 'hci_uart_register_dev()'. Signed-off-by: Arseniy Krasnov Signed-off-by: Luiz Augusto von Dentz

bluetooth: Fix typos in the comments

2024-11-14T20:28:07+00:00

Correctly spelled comments make it easier for the reader to understand the code. Fix typos: 'fragement' ==> 'fragment', 'genration' ==> 'generation', 'funciton' ==> 'function', 'Explitly' ==> 'Explicitly', 'explaination' ==> 'explanation', 'Tranlate' ==> 'Translate', 'immediatelly' ==> 'immediately', 'isntance' ==> 'instance', 'transmittion' ==> 'transmission', 'recevie' ==> 'receive', 'outselves' ==> 'ourselves', 'conrol' ==> 'control'. Signed-off-by: Yan Zhen Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Luiz Augusto von Dentz

Bluetooth: hci_ldisc: Use speed set by btattach as oper_speed

2024-09-10T17:05:13+00:00

Starting a BCM UART controller not defined as a platform device or a serdev with "btattach -B /dev/ttyS1 -P bcm -S 3000000" works fine but the serial port remains at the init_speed, i.e. 115200. The oper_speed is only set if a device is declared in ACPI, device tree or as a platform device. This commit copies the serial port speed fixed by hciattach to the oper_speed on line discipline opening. Signed-off-by: Frédéric Danis Signed-off-by: Luiz Augusto von Dentz