Merge tag 'android-8.1.0_r4' into lineage-15.1

Android 8.1.0 Release 4 (OPM1.171019.013)

# gpg: Signature made Tue Jan  2 18:42:55 2018 CST
# gpg:                using DSA key 4340D13570EF945E83810964E8AD3F819AB10E78
# gpg: Good signature from "The Android Open Source Project <[email protected]>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 4340 D135 70EF 945E 8381  0964 E8AD 3F81 9AB1 0E78

Author: invisiblek

libnetutils/packet.c

@@ -218,6 +218,20 @@ int receive_packet(int s, struct dhcp_msg *msg)
      * to construct the pseudo header used in the checksum calculation.
      */
     dhcp_size = ntohs(packet.udp.len) - sizeof(packet.udp);
+    /*
+     * check validity of dhcp_size.
+     * 1) cannot be negative or zero.
+     * 2) src buffer contains enough bytes to copy
+     * 3) cannot exceed destination buffer
+     */
+    if ((dhcp_size <= 0) ||
+        ((int)(nread - sizeof(struct iphdr) - sizeof(struct udphdr)) < dhcp_size) ||
+        ((int)sizeof(struct dhcp_msg) < dhcp_size)) {
+#if VERBOSE
+        ALOGD("Malformed Packet");
+#endif
+        return -1;
+    }
     saddr = packet.ip.saddr;
     daddr = packet.ip.daddr;
     nread = ntohs(packet.ip.tot_len);