Bluetooth: refactor malicious adv data check

stable inclusion
from stable-v5.10.96
commit 83d5196b65d1b29e27d7dd16a3b9b439fb1d2dba
bugzilla: https://gitee.com/openeuler/kernel/issues/I55NWB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=83d5196b65d1b29e27d7dd16a3b9b439fb1d2dba

--------------------------------

commit 899663be 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: NBrian Gix <brian.gix@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Cc: syphyr <syphyr@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYu Liao <liaoyu15@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/bluetooth/hci_event.c

@@ -5661,6 +5661,11 @@ static void hci_le_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		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];
@@ -5672,11 +5677,6 @@ static void hci_le_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		}
 
 		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);