diff options
| author | Prasad J Pandit <pjp@fedoraproject.org> | 2015-11-20 11:50:31 +0530 |
|---|---|---|
| committer | Jason Wang <jasowang@redhat.com> | 2015-12-07 21:43:48 +0800 |
| commit | 837f21aacf5a714c23ddaadbbc5212f9b661e3f7 (patch) | |
| tree | 62f3850f076bb0ba98ffb6594abeb4d30122f415 | |
| parent | 9596ef7c7b8528bedb240792ea1fb598543ad3c4 (diff) | |
| download | qemu-837f21aacf5a714c23ddaadbbc5212f9b661e3f7.zip qemu-837f21aacf5a714c23ddaadbbc5212f9b661e3f7.tar.gz qemu-837f21aacf5a714c23ddaadbbc5212f9b661e3f7.tar.bz2 | |
net: pcnet: add check to validate receive data size(CVE-2015-7504)
In loopback mode, pcnet_receive routine appends CRC code to the
receive buffer. If the data size given is same as the buffer size,
the appended CRC code overwrites 4 bytes after s->buffer. Added a
check to avoid that.
Reported by: Qinghao Tang <luodalongde@gmail.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>
| -rw-r--r-- | hw/net/pcnet.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c index 0eb3cc4..309c40b 100644 --- a/hw/net/pcnet.c +++ b/hw/net/pcnet.c @@ -1084,7 +1084,7 @@ ssize_t pcnet_receive(NetClientState *nc, const uint8_t *buf, size_t size_) uint32_t fcs = ~0; uint8_t *p = src; - while (p != &src[size-4]) + while (p != &src[size]) CRC(fcs, *p++); crc_err = (*(uint32_t *)p != htonl(fcs)); } @@ -1233,8 +1233,10 @@ static void pcnet_transmit(PCNetState *s) bcnt = 4096 - GET_FIELD(tmd.length, TMDL, BCNT); /* if multi-tmd packet outsizes s->buffer then skip it silently. - Note: this is not what real hw does */ - if (s->xmit_pos + bcnt > sizeof(s->buffer)) { + * Note: this is not what real hw does. + * Last four bytes of s->buffer are used to store CRC FCS code. + */ + if (s->xmit_pos + bcnt > sizeof(s->buffer) - 4) { s->xmit_pos = -1; goto txdone; } |