[PATCH 5.15 184/206] Bluetooth: Fix hci_suspend_sync crash

Greg Kroah-Hartman
2026-02-04T15:01:42Z

From: Ying Hsu <yinghsu@chromium.org>

[ Upstream commit 573ebae162111063eedc6c838a659ba628f66a0f ]

If hci_unregister_dev() frees the hci_dev object but hci_suspend_notifier
may still be accessing it, it can cause the program to crash.
Here's the call trace:
<4>[102152.653246] Call Trace:
<4>[102152.653254] hci_suspend_sync+0x109/0x301 [bluetooth]
<4>[102152.653259] hci_suspend_dev+0x78/0xcd [bluetooth]
<4>[102152.653263] hci_suspend_notifier+0x42/0x7a [bluetooth]
<4>[102152.653268] notifier_call_chain+0x43/0x6b
<4>[102152.653271] __blocking_notifier_call_chain+0x48/0x69
<4>[102152.653273] __pm_notifier_call_chain+0x22/0x39
<4>[102152.653276] pm_suspend+0x287/0x57c
<4>[102152.653278] state_store+0xae/0xe5
<4>[102152.653281] kernfs_fop_write+0x109/0x173
<4>[102152.653284] __vfs_write+0x16f/0x1a2
<4>[102152.653287] ? selinux_file_permission+0xca/0x16f
<4>[102152.653289] ? security_file_permission+0x36/0x109
<4>[102152.653291] vfs_write+0x114/0x21d
<4>[102152.653293] __x64_sys_write+0x7b/0xdb
<4>[102152.653296] do_syscall_64+0x59/0x194
<4>[102152.653299] entry_SYSCALL_64_after_hwframe+0x5c/0xc1

This patch holds the reference count of the hci_dev object while
processing it in hci_suspend_notifier to avoid potential crash
caused by the race condition.

Signed-off-by: Ying Hsu <yinghsu@chromium.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
[ Adjust context ]
Signed-off-by: Wenshan Lan <jetlan9@163.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/bluetooth/hci_core.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3706,6 +3706,9 @@ static int hci_suspend_notifier(struct n
int ret = 0;
u8 state = BT_RUNNING;

+ /* To avoid a potential race with hci_unregister_dev. */
+ hci_dev_hold(hdev);
+
/* If powering down, wait for completion. */
if (mgmt_powering_down(hdev)) {
set_bit(SUSPEND_POWERING_DOWN, hdev->suspend_tasks);
@@ -3757,6 +3760,7 @@ done:
bt_dev_err(hdev, "Suspend notifier action (%lu) failed: %d",
action, ret);

+ hci_dev_put(hdev);
return NOTIFY_DONE;
}