FAILED: patch "[PATCH] Bluetooth: Fix slab-out-of-bounds read in" failed to apply to 4.9-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f7e0e8b2f1b0a09b527885babda3e912ba820798 Mon Sep 17 00:00:00 2001
From: Peilin Ye <yepeilin.cs@gmail.com>
Date: Wed, 9 Sep 2020 03:17:00 -0400
Subject: [PATCH] Bluetooth: Fix slab-out-of-bounds read in
 hci_le_direct_adv_report_evt()

`num_reports` is not being properly checked. A malformed event packet with
a large `num_reports` number makes hci_le_direct_adv_report_evt() read out
of bounds. Fix it.

Cc: stable@vger.kernel.org
Fixes: 2f010b55884e ("Bluetooth: Add support for handling LE Direct Advertising Report events")
Reported-and-tested-by: syzbot+24ebd650e20bd263ca01@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=24ebd650e20bd263ca01
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index e72982b69f6b..17a72695865b 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -5873,21 +5873,19 @@ static void hci_le_direct_adv_report_evt(struct hci_dev *hdev,
 					 struct sk_buff *skb)
 {
 	u8 num_reports = skb->data[0];
-	void *ptr = &skb->data[1];
+	struct hci_ev_le_direct_adv_info *ev = (void *)&skb->data[1];
 
-	hci_dev_lock(hdev);
+	if (!num_reports || skb->len < num_reports * sizeof(*ev) + 1)
+		return;
 
-	while (num_reports--) {
-		struct hci_ev_le_direct_adv_info *ev = ptr;
+	hci_dev_lock(hdev);
 
+	for (; num_reports; num_reports--, ev++)
 		process_adv_report(hdev, ev->evt_type, &ev->bdaddr,
 				   ev->bdaddr_type, &ev->direct_addr,
 				   ev->direct_addr_type, ev->rssi, NULL, 0,
 				   false);
 
-		ptr += sizeof(*ev);
-	}
-
 	hci_dev_unlock(hdev);
 }