Fix null pointer deref in hci_phy_link_complete_evt, there was no checking 
there for
the hcon->amp_mgr->l2cap_conn->hconn, and also in hci_cmd_work, for
hdev->sent_cmd. 

To fix this issue Add pointer checking in hci_cmd_work and
hci_phy_link_complete_evt.
[Linux-next-20200827]

Reported-by: syzbot+0bef568258653cff2...@syzkaller.appspotmail.com
Link: 
https://syzkaller.appspot.com/bug?id=0d93140da5a82305a66a136af99b088b75177b99
Signed-off-by: Anmol Karn <anmol.karan...@gmail.com>
---
 net/bluetooth/hci_core.c  | 4 ++++
 net/bluetooth/hci_event.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 68bfe57b6625..533048d2a624 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -4922,6 +4922,10 @@ static void hci_cmd_work(struct work_struct *work)
 
                kfree_skb(hdev->sent_cmd);
 
+               if(hdev->sent_cmd) {
+                       hdev->sent_cmd = skb_clone(skb, GFP_KERNEL);
+               }
+
                hdev->sent_cmd = skb_clone(skb, GFP_KERNEL);
                if (hdev->sent_cmd) {
                        if (hci_req_status_pend(hdev))
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 4b7fc430793c..c621c8a20ea4 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4941,6 +4941,10 @@ static void hci_phy_link_complete_evt(struct hci_dev 
*hdev,
                hci_dev_unlock(hdev);
                return;
        }
+       if(!(hcon->amp_mgr->l2cap_conn->hcon)) {
+               hci_dev_unlock(hdev);
+               return;
+       }
 
        bredr_hcon = hcon->amp_mgr->l2cap_conn->hcon;
 
-- 
2.28.0

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