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pcnet: fix Negative array index read 

s->xmit_pos maybe assigned to a negative value (-1),
but in this branch variable s->xmit_pos as an index to
array s->buffer. Let's add a check for s->xmit_pos.

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Gonglei 2014-11-20 19:35:02 +08:00 committed by Stefan Hajnoczi
parent 8db804ac41
commit 7b50d00911
1 changed files with 32 additions and 27 deletions
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59
hw/net/pcnet.c
View File

@ -1212,7 +1212,7 @@ static void pcnet_transmit(PCNetState *s)
hwaddr xmit_cxda = 0;
int count = CSR_XMTRL(s)-1;
int add_crc = 0;
int bcnt;
s->xmit_pos = -1;
if (!CSR_TXON(s)) {
@ -1247,35 +1247,40 @@ static void pcnet_transmit(PCNetState *s)
s->xmit_pos = -1;
goto txdone;
}
if (!GET_FIELD(tmd.status, TMDS, ENP)) {
int bcnt = 4096 - GET_FIELD(tmd.length, TMDL, BCNT);
s->phys_mem_read(s->dma_opaque, PHYSADDR(s, tmd.tbadr),
s->buffer + s->xmit_pos, bcnt, CSR_BSWP(s));
s->xmit_pos += bcnt;
} else if (s->xmit_pos >= 0) {
int bcnt = 4096 - GET_FIELD(tmd.length, TMDL, BCNT);
s->phys_mem_read(s->dma_opaque, PHYSADDR(s, tmd.tbadr),
s->buffer + s->xmit_pos, bcnt, CSR_BSWP(s));
s->xmit_pos += bcnt;
#ifdef PCNET_DEBUG
printf("pcnet_transmit size=%d\n", s->xmit_pos);
#endif
if (CSR_LOOP(s)) {
if (BCR_SWSTYLE(s) == 1)
add_crc = !GET_FIELD(tmd.status, TMDS, NOFCS);
s->looptest = add_crc ? PCNET_LOOPTEST_CRC : PCNET_LOOPTEST_NOCRC;
pcnet_receive(qemu_get_queue(s->nic), s->buffer, s->xmit_pos);
s->looptest = 0;
} else
if (s->nic)
qemu_send_packet(qemu_get_queue(s->nic), s->buffer,
s->xmit_pos);
s->csr[0] &= ~0x0008; /* clear TDMD */
s->csr[4] |= 0x0004; /* set TXSTRT */
s->xmit_pos = -1;
if (s->xmit_pos < 0) {
goto txdone;
}
bcnt = 4096 - GET_FIELD(tmd.length, TMDL, BCNT);
s->phys_mem_read(s->dma_opaque, PHYSADDR(s, tmd.tbadr),
s->buffer + s->xmit_pos, bcnt, CSR_BSWP(s));
s->xmit_pos += bcnt;
if (!GET_FIELD(tmd.status, TMDS, ENP)) {
goto txdone;
}
#ifdef PCNET_DEBUG
printf("pcnet_transmit size=%d\n", s->xmit_pos);
#endif
if (CSR_LOOP(s)) {
if (BCR_SWSTYLE(s) == 1)
add_crc = !GET_FIELD(tmd.status, TMDS, NOFCS);
s->looptest = add_crc ? PCNET_LOOPTEST_CRC : PCNET_LOOPTEST_NOCRC;
pcnet_receive(qemu_get_queue(s->nic), s->buffer, s->xmit_pos);
s->looptest = 0;
} else {
if (s->nic) {
qemu_send_packet(qemu_get_queue(s->nic), s->buffer,
s->xmit_pos);
}
}
s->csr[0] &= ~0x0008; /* clear TDMD */
s->csr[4] |= 0x0004; /* set TXSTRT */
s->xmit_pos = -1;
txdone:
SET_FIELD(&tmd.status, TMDS, OWN, 0);
TMDSTORE(&tmd, PHYSADDR(s,CSR_CXDA(s)));