blob: 2e3352d88b625bdcee6633d8dd553d1364051229 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
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>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
hw/net/pcnet.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c
index 3437376..5f55591 100644
--- a/hw/net/pcnet.c
+++ b/hw/net/pcnet.c
@@ -1085,7 +1085,7 @@ 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));
}
@@ -1234,8 +1234,10 @@ 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;
}
--
2.4.3
|
