debian/patches/CVE-2015-3209-pcnet-oob.patch

   1 From 9f7c594c006289ad41169b854d70f5da6e400a2a Mon Sep 17 00:00:00 2001
   2 From: Petr Matousek <pmatouse@redhat.com>
   3 Date: Sun, 24 May 2015 10:53:44 +0200
   4 Subject: [PATCH] pcnet: force the buffer access to be in bounds during tx
   5
   6 4096 is the maximum length per TMD and it is also currently the size of
   7 the relay buffer pcnet driver uses for sending the packet data to QEMU
   8 for further processing. With packet spanning multiple TMDs it can
   9 happen that the overall packet size will be bigger than sizeof(buffer),
  10 which results in memory corruption.
  11
  12 Fix this by only allowing to queue maximum sizeof(buffer) bytes.
  13
  14 This is CVE-2015-3209.
  15
  16 [Fixed 3-space indentation to QEMU's 4-space coding standard.
  17 --Stefan]
  18
  19 Signed-off-by: Petr Matousek <pmatouse@redhat.com>
  20 Reported-by: Matt Tait <matttait@google.com>
  21 Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
  22 Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
  23 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
  24 ---
  25  hw/net/pcnet.c | 8 ++++++++
  26  1 file changed, 8 insertions(+)
  27
  28 diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c
  29 index bdfd38f..68b9981 100644
  30 --- a/hw/net/pcnet.c
  31 +++ b/hw/net/pcnet.c
  32 @@ -1241,6 +1241,14 @@ static void pcnet_transmit(PCNetState *s)
  33          }
  34
  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 +            s->xmit_pos = -1;
  41 +            goto txdone;
  42 +        }
  43 +
  44          s->phys_mem_read(s->dma_opaque, PHYSADDR(s, tmd.tbadr),
  45                           s->buffer + s->xmit_pos, bcnt, CSR_BSWP(s));
  46          s->xmit_pos += bcnt;
  47 --
  48 2.1.4
  49