[Qemu-commits] [qemu/qemu] edc243: virtio-net: fix guest-triggerable buffer overrun

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/qemu/qemu
  Commit: edc243851279e3393000b28b6b69454cae1190ef
      
https://github.com/qemu/qemu/commit/edc243851279e3393000b28b6b69454cae1190ef
  Author: Michael S. Tsirkin <address@hidden>
  Date:   2014-04-11 (Fri, 11 Apr 2014)

  Changed paths:
    M hw/net/virtio-net.c

  Log Message:
  -----------
  virtio-net: fix guest-triggerable buffer overrun

When VM guest programs multicast addresses for
a virtio net card, it supplies a 32 bit
entries counter for the number of addresses.
These addresses are read into tail portion of
a fixed macs array which has size MAC_TABLE_ENTRIES,
at offset equal to in_use.

To avoid overflow of this array by guest, qemu attempts
to test the size as follows:
-    if (in_use + mac_data.entries <= MAC_TABLE_ENTRIES) {

however, as mac_data.entries is uint32_t, this sum
can overflow, e.g. if in_use is 1 and mac_data.entries
is 0xffffffff then in_use + mac_data.entries will be 0.

Qemu will then read guest supplied buffer into this
memory, overflowing buffer on heap.

CVE-2014-0150

Cc: address@hidden
Signed-off-by: Michael S. Tsirkin <address@hidden>
Message-id: address@hidden
Reviewed-by: Michael Tokarev <address@hidden>
Signed-off-by: Peter Maydell <address@hidden>