This is a note to let you know that I've just added the patch titled
Bluetooth: Fix hci_suspend_sync crash
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bluetooth-fix-hci_suspend_sync-crash.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b9cbcb26e426ef7b66b372237b0a3ba9e4aefce4
Author: Ying Hsu <yinghsu@xxxxxxxxxxxx>
Date: Wed Jul 5 21:06:47 2023 +0000
Bluetooth: Fix hci_suspend_sync crash
[ 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@xxxxxxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 146553c0054f6..fa4dd5fab0d44 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2436,6 +2436,9 @@ static int hci_suspend_notifier(struct notifier_block *nb, unsigned long action,
if (hci_dev_test_flag(hdev, HCI_USER_CHANNEL))
return NOTIFY_DONE;
+ /* To avoid a potential race with hci_unregister_dev. */
+ hci_dev_hold(hdev);
+
if (action == PM_SUSPEND_PREPARE)
ret = hci_suspend_dev(hdev);
else if (action == PM_POST_SUSPEND)
@@ -2445,6 +2448,7 @@ static int hci_suspend_notifier(struct notifier_block *nb, unsigned long action,
bt_dev_err(hdev, "Suspend notifier action (%lu) failed: %d",
action, ret);
+ hci_dev_put(hdev);
return NOTIFY_DONE;
}
