[PATCH] Bluetooth: hci_uart: add missing NULL check in h5_enqueue

[Pavel Skripkin <paskripkin@gmail.com>]

Syzbot hit general protection fault in __pm_runtime_resume(). The problem
was in missing NULL check.

hu->serdev can be NULL and we should not blindly pass &serdev->dev
somewhere, since it will cause GPF.

Reported-by: syzbot+b9bd12fbed3485a3e51f@syzkaller.appspotmail.com
Fixes: d9dd833cf6d2 ("Bluetooth: hci_h5: Add runtime suspend")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 drivers/bluetooth/hci_h5.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
index 34286ffe0568..7ac6908a4dfb 100644
--- a/drivers/bluetooth/hci_h5.c
+++ b/drivers/bluetooth/hci_h5.c
@@ -629,9 +629,11 @@ static int h5_enqueue(struct hci_uart *hu, struct sk_buff *skb)
 		break;
 	}
 
-	pm_runtime_get_sync(&hu->serdev->dev);
-	pm_runtime_mark_last_busy(&hu->serdev->dev);
-	pm_runtime_put_autosuspend(&hu->serdev->dev);
+	if (hu->serdev) {
+		pm_runtime_get_sync(&hu->serdev->dev);
+		pm_runtime_mark_last_busy(&hu->serdev->dev);
+		pm_runtime_put_autosuspend(&hu->serdev->dev);
+	}
 
 	return 0;
 }
-- 
2.35.1