linux-kernel - [PATCH 5.15 161/171] Bluetooth: refactor malicious adv data check

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Message-Id: <20220131105235.463268057@linuxfoundation.org>
Date:   Mon, 31 Jan 2022 11:57:06 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Brian Gix <brian.gix@...el.com>,
        Marcel Holtmann <marcel@...tmann.org>,
        syphyr <syphyr@...il.com>
Subject: [PATCH 5.15 161/171] Bluetooth: refactor malicious adv data check

From: Brian Gix <brian.gix@...el.com>

commit 899663be5e75dc0174dc8bda0b5e6826edf0b29a upstream.

Check for out-of-bound read was being performed at the end of while
num_reports loop, and would fill journal with false positives. Added
check to beginning of loop processing so that it doesn't get checked
after ptr has been advanced.

Signed-off-by: Brian Gix <brian.gix@...el.com>
Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
Cc: syphyr <syphyr@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/bluetooth/hci_event.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -5782,6 +5782,11 @@ static void hci_le_adv_report_evt(struct
 		struct hci_ev_le_advertising_info *ev = ptr;
 		s8 rssi;
 
+		if (ptr > (void *)skb_tail_pointer(skb) - sizeof(*ev)) {
+			bt_dev_err(hdev, "Malicious advertising data.");
+			break;
+		}
+
 		if (ev->length <= HCI_MAX_AD_LENGTH &&
 		    ev->data + ev->length <= skb_tail_pointer(skb)) {
 			rssi = ev->data[ev->length];
@@ -5793,11 +5798,6 @@ static void hci_le_adv_report_evt(struct
 		}
 
 		ptr += sizeof(*ev) + ev->length + 1;
-
-		if (ptr > (void *) skb_tail_pointer(skb) - sizeof(*ev)) {
-			bt_dev_err(hdev, "Malicious advertising data. Stopping processing");
-			break;
-		}
 	}
 
 	hci_dev_unlock(hdev);