Syzkaller reports a potential circular dependency leading to deadlock in 5.10 and 5.15 stable releases since the commit 92d4abd66f70 ("Bluetooth: vhci: Fix race when opening vhci device") that caused this crash was backported to these branches. The problem has been fixed by the following upstream patch that was adapted to 5.10 and 5.15. All of the changes made to the patch in order to adapt it are described at the end of commit message.
This patch has already been backported to the following stable branches: v6.6 - https://lore.kernel.org/stable/20231230115814.038261305@linuxfoundation.org/ v6.1 - https://lore.kernel.org/stable/20231230115807.749489379@linuxfoundation.org/
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
From: Ying Hsu yinghsu@chromium.org
commit 769bf60e17ee1a56a81e7c031192c3928312c52e upstream.
syzbot found a potential circular dependency leading to a deadlock: -> #3 (&hdev->req_lock){+.+.}-{3:3}: __mutex_lock_common+0x1b6/0x1bc2 kernel/locking/mutex.c:599 __mutex_lock kernel/locking/mutex.c:732 [inline] mutex_lock_nested+0x17/0x1c kernel/locking/mutex.c:784 hci_dev_do_close+0x3f/0x9f net/bluetooth/hci_core.c:551 hci_rfkill_set_block+0x130/0x1ac net/bluetooth/hci_core.c:935 rfkill_set_block+0x1e6/0x3b8 net/rfkill/core.c:345 rfkill_fop_write+0x2d8/0x672 net/rfkill/core.c:1274 vfs_write+0x277/0xcf5 fs/read_write.c:594 ksys_write+0x19b/0x2bd fs/read_write.c:650 do_syscall_x64 arch/x86/entry/common.c:55 [inline] do_syscall_64+0x51/0xba arch/x86/entry/common.c:93 entry_SYSCALL_64_after_hwframe+0x61/0xcb
-> #2 (rfkill_global_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1b6/0x1bc2 kernel/locking/mutex.c:599 __mutex_lock kernel/locking/mutex.c:732 [inline] mutex_lock_nested+0x17/0x1c kernel/locking/mutex.c:784 rfkill_register+0x30/0x7e3 net/rfkill/core.c:1045 hci_register_dev+0x48f/0x96d net/bluetooth/hci_core.c:2622 __vhci_create_device drivers/bluetooth/hci_vhci.c:341 [inline] vhci_create_device+0x3ad/0x68f drivers/bluetooth/hci_vhci.c:374 vhci_get_user drivers/bluetooth/hci_vhci.c:431 [inline] vhci_write+0x37b/0x429 drivers/bluetooth/hci_vhci.c:511 call_write_iter include/linux/fs.h:2109 [inline] new_sync_write fs/read_write.c:509 [inline] vfs_write+0xaa8/0xcf5 fs/read_write.c:596 ksys_write+0x19b/0x2bd fs/read_write.c:650 do_syscall_x64 arch/x86/entry/common.c:55 [inline] do_syscall_64+0x51/0xba arch/x86/entry/common.c:93 entry_SYSCALL_64_after_hwframe+0x61/0xcb
-> #1 (&data->open_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1b6/0x1bc2 kernel/locking/mutex.c:599 __mutex_lock kernel/locking/mutex.c:732 [inline] mutex_lock_nested+0x17/0x1c kernel/locking/mutex.c:784 vhci_send_frame+0x68/0x9c drivers/bluetooth/hci_vhci.c:75 hci_send_frame+0x1cc/0x2ff net/bluetooth/hci_core.c:2989 hci_sched_acl_pkt net/bluetooth/hci_core.c:3498 [inline] hci_sched_acl net/bluetooth/hci_core.c:3583 [inline] hci_tx_work+0xb94/0x1a60 net/bluetooth/hci_core.c:3654 process_one_work+0x901/0xfb8 kernel/workqueue.c:2310 worker_thread+0xa67/0x1003 kernel/workqueue.c:2457 kthread+0x36a/0x430 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
-> #0 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3787 [inline] __lock_acquire+0x2d32/0x77fa kernel/locking/lockdep.c:5011 lock_acquire+0x273/0x4d5 kernel/locking/lockdep.c:5622 __flush_work+0xee/0x19f kernel/workqueue.c:3090 hci_dev_close_sync+0x32f/0x1113 net/bluetooth/hci_sync.c:4352 hci_dev_do_close+0x47/0x9f net/bluetooth/hci_core.c:553 hci_rfkill_set_block+0x130/0x1ac net/bluetooth/hci_core.c:935 rfkill_set_block+0x1e6/0x3b8 net/rfkill/core.c:345 rfkill_fop_write+0x2d8/0x672 net/rfkill/core.c:1274 vfs_write+0x277/0xcf5 fs/read_write.c:594 ksys_write+0x19b/0x2bd fs/read_write.c:650 do_syscall_x64 arch/x86/entry/common.c:55 [inline] do_syscall_64+0x51/0xba arch/x86/entry/common.c:93 entry_SYSCALL_64_after_hwframe+0x61/0xcb
This change removes the need for acquiring the open_mutex in vhci_send_frame, thus eliminating the potential deadlock while maintaining the required packet ordering.
Fixes: 92d4abd66f70 ("Bluetooth: vhci: Fix race when opening vhci device") Signed-off-by: Ying Hsu yinghsu@chromium.org Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com [Daniil: In order to adapt this patch to branches 5.10 and 5.15 redundant fields of struct vhci_data were removed as these fields are not used in 5.10 and 5.15.] Signed-off-by: Daniil Dulov d.dulov@aladdin.ru --- drivers/bluetooth/hci_vhci.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c index 31d70bad83d2..93773ec90795 100644 --- a/drivers/bluetooth/hci_vhci.c +++ b/drivers/bluetooth/hci_vhci.c @@ -11,6 +11,7 @@ #include <linux/module.h> #include <asm/unaligned.h>
+#include <linux/atomic.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/slab.h> @@ -37,6 +38,7 @@ struct vhci_data {
struct mutex open_mutex; struct delayed_work open_timeout; + atomic_t initialized; };
static int vhci_open_dev(struct hci_dev *hdev) @@ -68,11 +70,10 @@ static int vhci_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);
- mutex_lock(&data->open_mutex); skb_queue_tail(&data->readq, skb); - mutex_unlock(&data->open_mutex);
- wake_up_interruptible(&data->read_wait); + if (atomic_read(&data->initialized)) + wake_up_interruptible(&data->read_wait); return 0; }
@@ -139,7 +140,8 @@ static int __vhci_create_device(struct vhci_data *data, __u8 opcode) skb_put_u8(skb, 0xff); skb_put_u8(skb, opcode); put_unaligned_le16(hdev->id, skb_put(skb, 2)); - skb_queue_tail(&data->readq, skb); + skb_queue_head(&data->readq, skb); + atomic_inc(&data->initialized);
wake_up_interruptible(&data->read_wait); return 0;
linux-stable-mirror@lists.linaro.org
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Daniil Dulov