debian/patches/CVE-2015-7504-pcnet-validate-size.patch

   1 From 837f21aacf5a714c23ddaadbbc5212f9b661e3f7 Mon Sep 17 00:00:00 2001
   2 From: Prasad J Pandit <pjp@fedoraproject.org>
   3 Date: Fri, 20 Nov 2015 11:50:31 +0530
   4 Subject: [PATCH] net: pcnet: add check to validate receive data
   5  size(CVE-2015-7504)
   6
   7 In loopback mode, pcnet_receive routine appends CRC code to the
   8 receive buffer. If the data size given is same as the buffer size,
   9 the appended CRC code overwrites 4 bytes after s->buffer. Added a
  10 check to avoid that.
  11
  12 Reported by: Qinghao Tang <luodalongde@gmail.com>
  13 Cc: qemu-stable@nongnu.org
  14 Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
  15 Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
  16 Signed-off-by: Jason Wang <jasowang@redhat.com>
  17 ---
  18  hw/net/pcnet.c | 8 +++++---
  19  1 file changed, 5 insertions(+), 3 deletions(-)
  20
  21 diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c
  22 index 0eb3cc4..309c40b 100644
  23 --- a/hw/net/pcnet.c
  24 +++ b/hw/net/pcnet.c
  25 @@ -1084,7 +1084,7 @@ ssize_t pcnet_receive(NetClientState *nc, const uint8_t *buf, size_t size_)
  26                  uint32_t fcs = ~0;
  27                  uint8_t *p = src;
  28
  29 -                while (p != &src[size-4])
  30 +                while (p != &src[size])
  31                      CRC(fcs, *p++);
  32                  crc_err = (*(uint32_t *)p != htonl(fcs));
  33              }
  34 @@ -1233,8 +1233,10 @@ static void pcnet_transmit(PCNetState *s)
  35          bcnt = 4096 - GET_FIELD(tmd.length, TMDL, BCNT);
  36
  37          /* if multi-tmd packet outsizes s->buffer then skip it silently.
  38 -           Note: this is not what real hw does */
  39 -        if (s->xmit_pos + bcnt > sizeof(s->buffer)) {
  40 +         * Note: this is not what real hw does.
  41 +         * Last four bytes of s->buffer are used to store CRC FCS code.
  42 +         */
  43 +        if (s->xmit_pos + bcnt > sizeof(s->buffer) - 4) {
  44              s->xmit_pos = -1;
  45              goto txdone;
  46          }
  47 --
  48 2.1.4
  49