Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756420AbcKBUHU (ORCPT ); Wed, 2 Nov 2016 16:07:20 -0400 Received: from einhorn.in-berlin.de ([192.109.42.8]:41839 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755938AbcKBUHT (ORCPT ); Wed, 2 Nov 2016 16:07:19 -0400 X-Envelope-From: stefanr@s5r6.in-berlin.de Date: Wed, 2 Nov 2016 21:07:08 +0100 From: Stefan Richter To: linux1394-devel@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org, Eyal Itkin Subject: [PATCH 1/3] firewire: net: guard against rx buffer overflows Message-ID: <20161102210708.12212ada@kant> In-Reply-To: <20161102210554.23b24d74@kant> References: <20161102210554.23b24d74@kant> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3686 Lines: 127 Date: Sat, 29 Oct 2016 21:28:18 +0200 The IP-over-1394 driver firewire-net lacked input validation when handling incoming fragmented datagrams. A maliciously formed fragment with a respectively large datagram_offset would cause a memcpy past the datagram buffer. So, drop any packets carrying a fragment with offset + length larger than datagram_size. In addition, ensure that - GASP header, unfragmented encapsulation header, or fragment encapsulation header actually exists before we access it, - the encapsulated datagram or fragment is of nonzero size. Reported-by: Eyal Itkin Cc: stable@vger.kernel.org Signed-off-by: Stefan Richter --- drivers/firewire/net.c | 51 ++++++++++++++++++++++++++++------------- 1 file changed, 35 insertions(+), 16 deletions(-) --- a/drivers/firewire/net.c +++ b/drivers/firewire/net.c @@ -578,6 +578,9 @@ static int fwnet_incoming_packet(struct int retval; u16 ether_type; + if (len <= RFC2374_UNFRAG_HDR_SIZE) + return 0; + hdr.w0 = be32_to_cpu(buf[0]); lf = fwnet_get_hdr_lf(&hdr); if (lf == RFC2374_HDR_UNFRAG) { @@ -602,7 +605,12 @@ static int fwnet_incoming_packet(struct return fwnet_finish_incoming_packet(net, skb, source_node_id, is_broadcast, ether_type); } + /* A datagram fragment has been received, now the fun begins. */ + + if (len <= RFC2374_FRAG_HDR_SIZE) + return 0; + hdr.w1 = ntohl(buf[1]); buf += 2; len -= RFC2374_FRAG_HDR_SIZE; @@ -616,6 +624,9 @@ static int fwnet_incoming_packet(struct datagram_label = fwnet_get_hdr_dgl(&hdr); dg_size = fwnet_get_hdr_dg_size(&hdr); /* ??? + 1 */ + if (fg_off + len > dg_size) + return 0; + spin_lock_irqsave(&dev->lock, flags); peer = fwnet_peer_find_by_node_id(dev, source_node_id, generation); @@ -722,6 +733,22 @@ static void fwnet_receive_packet(struct fw_send_response(card, r, rcode); } +static int gasp_source_id(__be32 *p) +{ + return be32_to_cpu(p[0]) >> 16; +} + +static u32 gasp_specifier_id(__be32 *p) +{ + return (be32_to_cpu(p[0]) & 0xffff) << 8 | + (be32_to_cpu(p[1]) & 0xff000000) >> 24; +} + +static u32 gasp_version(__be32 *p) +{ + return be32_to_cpu(p[1]) & 0xffffff; +} + static void fwnet_receive_broadcast(struct fw_iso_context *context, u32 cycle, size_t header_length, void *header, void *data) { @@ -731,9 +758,6 @@ static void fwnet_receive_broadcast(stru __be32 *buf_ptr; int retval; u32 length; - u16 source_node_id; - u32 specifier_id; - u32 ver; unsigned long offset; unsigned long flags; @@ -750,22 +774,17 @@ static void fwnet_receive_broadcast(stru spin_unlock_irqrestore(&dev->lock, flags); - specifier_id = (be32_to_cpu(buf_ptr[0]) & 0xffff) << 8 - | (be32_to_cpu(buf_ptr[1]) & 0xff000000) >> 24; - ver = be32_to_cpu(buf_ptr[1]) & 0xffffff; - source_node_id = be32_to_cpu(buf_ptr[0]) >> 16; - - if (specifier_id == IANA_SPECIFIER_ID && - (ver == RFC2734_SW_VERSION + if (length > IEEE1394_GASP_HDR_SIZE && + gasp_specifier_id(buf_ptr) == IANA_SPECIFIER_ID && + (gasp_version(buf_ptr) == RFC2734_SW_VERSION #if IS_ENABLED(CONFIG_IPV6) - || ver == RFC3146_SW_VERSION + || gasp_version(buf_ptr) == RFC3146_SW_VERSION #endif - )) { - buf_ptr += 2; - length -= IEEE1394_GASP_HDR_SIZE; - fwnet_incoming_packet(dev, buf_ptr, length, source_node_id, + )) + fwnet_incoming_packet(dev, buf_ptr + 2, + length - IEEE1394_GASP_HDR_SIZE, + gasp_source_id(buf_ptr), context->card->generation, true); - } packet.payload_length = dev->rcv_buffer_size; packet.interrupt = 1; -- Stefan Richter -======----- =-== ---=- http://arcgraph.de/sr/