[Linux-kernel-mentees] [PATCH] net: bluetooth: Fix null pointer dereference in hci_event_packet()

Anmol Karn anmol.karan123 at gmail.com
Tue Sep 29 17:32:31 UTC 2020

AMP_MGR is getting derefernced in hci_phy_link_complete_evt(), when called from hci_event_packet() and there is a possibility, that hcon->amp_mgr may not be found when accessing after initialization of hcon.

- net/bluetooth/hci_event.c:4945
The bug seems to get triggered in this line:

bredr_hcon = hcon->amp_mgr->l2cap_conn->hcon;

Fix it by adding a NULL check for the hcon->amp_mgr before checking the ev-status.

Fixes: d5e911928bd8 ("Bluetooth: AMP: Process Physical Link Complete evt") 
Reported-and-tested-by: syzbot+0bef568258653cff272f at syzkaller.appspotmail.com 
Link: https://syzkaller.appspot.com/bug?extid=0bef568258653cff272f 
Signed-off-by: Anmol Karn <anmol.karan123 at gmail.com>
Cahnge in v2:
  - Replaced IS_ERR_OR_NULL check with NULL check only (Suggested by: Dan Carpenter <dan.carpenter at oracle.com>)
  - Added "Fixes:" tag (Suggested by: Dan Carpenter <dan.carpenter at oracle.com>)

 net/bluetooth/hci_event.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 4b7fc430793c..b084142c578e 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4936,6 +4936,11 @@ static void hci_phy_link_complete_evt(struct hci_dev *hdev,
+	if (!hcon->amp_mgr) {
+		hci_dev_unlock(hdev);
+		return 0;
+	}
 	if (ev->status) {

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