| Message ID | 1454669651-29411-1-git-send-email-ppandit@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
+-- On Fri, 5 Feb 2016, P J P wrote --+ | From: Prasad J Pandit <pjp@fedoraproject.org> | | When processing remote NDIS control message packets, the USB Net | device emulator uses a fixed length(4096) data buffer. The incoming | informationBufferOffset & Length combination could cross that range. | Check control message buffer offsets and length to avoid it. | | Reported-by: Qinghao Tang <luodalongde@gmail.com> ...ping! -- - P J P 47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
+-- On Tue, 9 Feb 2016, P J P wrote --+ | +-- On Fri, 5 Feb 2016, P J P wrote --+ | | From: Prasad J Pandit <pjp@fedoraproject.org> | | | | When processing remote NDIS control message packets, the USB Net | | device emulator uses a fixed length(4096) data buffer. The incoming | | informationBufferOffset & Length combination could cross that range. | | Check control message buffer offsets and length to avoid it. | | | | Reported-by: Qinghao Tang <luodalongde@gmail.com> | | ...ping! Ping...Gerd? -- - P J P 47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
On Mo, 2016-02-15 at 09:56 +0530, P J P wrote: > +-- On Tue, 9 Feb 2016, P J P wrote --+ > | +-- On Fri, 5 Feb 2016, P J P wrote --+ > | | From: Prasad J Pandit <pjp@fedoraproject.org> > | | > | | When processing remote NDIS control message packets, the USB Net > | | device emulator uses a fixed length(4096) data buffer. The incoming > | | informationBufferOffset & Length combination could cross that range. > | | Check control message buffer offsets and length to avoid it. > | | > | | Reported-by: Qinghao Tang <luodalongde@gmail.com> > | > | ...ping! > > Ping...Gerd? Was offline for a week, will look soonish (have a email backlog to process now ...) cheers, Gerd
> diff --git a/hw/usb/core.c b/hw/usb/core.c > index d0025db..9d90ec7 100644 > --- a/hw/usb/core.c > +++ b/hw/usb/core.c > @@ -128,9 +128,16 @@ static void do_token_setup(USBDevice *s, USBPacket *p) > } > > usb_packet_copy(p, s->setup_buf, p->iov.size); > + s->setup_index = 0; > p->actual_length = 0; > s->setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; > - s->setup_index = 0; > + if (s->setup_len > sizeof(s->data_buf)) { > + fprintf(stderr, > + "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", > + s->setup_len, sizeof(s->data_buf)); > + p->status = USB_RET_STALL; > + return; > + } > > request = (s->setup_buf[0] << 8) | s->setup_buf[1]; > value = (s->setup_buf[3] << 8) | s->setup_buf[2]; > @@ -151,13 +158,6 @@ static void do_token_setup(USBDevice *s, USBPacket *p) > } > s->setup_state = SETUP_STATE_DATA; > } else { > - if (s->setup_len > sizeof(s->data_buf)) { > - fprintf(stderr, > - "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", > - s->setup_len, sizeof(s->data_buf)); > - p->status = USB_RET_STALL; > - return; > - } > if (s->setup_len == 0) > s->setup_state = SETUP_STATE_ACK; > else Moves up the check so it is done for every control xfer. Good. > @@ -172,11 +172,18 @@ static void do_token_in(USBDevice *s, USBPacket *p) > int request, value, index; > > assert(p->ep->nr == 0); > + if (s->setup_len > sizeof(s->data_buf)) { > + fprintf(stderr, > + "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", > + s->setup_len, sizeof(s->data_buf)); > + p->status = USB_RET_STALL; > + return; > + } Why this is needed? All control transfers go through do_token_setup first, so with the check moved in do_token_setup we should never ever trigger it here ... > - if (bufoffs + buflen > length) > + if (buflen > length || bufoffs >= length || bufoffs + buflen > length) { > return USB_RET_STALL; > + } What is this? Not mentioned in the commit message. Looks like integer overflow prevention to me (if correct: separate patch with proper commit message please). thanks, Gerd
Hello Gerd,
+-- On Tue, 16 Feb 2016, Gerd Hoffmann wrote --+
| Moves up the check so it is done for every control xfer. Good.
...
| Why this is needed? All control transfers go through do_token_setup
| first, so with the check moved in do_token_setup we should never ever
| trigger it here ...
I see, okay.
| > - if (bufoffs + buflen > length)
| > + if (buflen > length || bufoffs >= length || bufoffs + buflen > length) {
| > return USB_RET_STALL;
| > + }
|
| What is this? Not mentioned in the commit message. Looks like integer
| overflow prevention to me (if correct: separate patch with proper commit
| message please).
That's right. I've sent separate revised patches for the above two changes.
Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
+-- On Tue, 16 Feb 2016, Gerd Hoffmann wrote --+
| > @@ -172,11 +172,18 @@ static void do_token_in(USBDevice *s, USBPacket *p)
| > assert(p->ep->nr == 0);
| > + if (s->setup_len > sizeof(s->data_buf)) {
| > + fprintf(stderr,
| > + "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n",
| > + s->setup_len, sizeof(s->data_buf));
| > + p->status = USB_RET_STALL;
| > + return;
| > + }
|
| Why this is needed? All control transfers go through do_token_setup
| first, so with the check moved in do_token_setup we should never ever
| trigger it here ...
usb_handle_packet
-> usb_process_one
-> do_token_in
Is it possible for a guest to call do_token_in, without calling
do_token_setup first? Most drivers seem to have their own 'usb_packet_setup'
routine. (to confirm)
Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
On Mi, 2016-02-17 at 13:55 +0530, P J P wrote: > +-- On Tue, 16 Feb 2016, Gerd Hoffmann wrote --+ > | > @@ -172,11 +172,18 @@ static void do_token_in(USBDevice *s, USBPacket *p) > | > assert(p->ep->nr == 0); > | > + if (s->setup_len > sizeof(s->data_buf)) { > | > + fprintf(stderr, > | > + "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", > | > + s->setup_len, sizeof(s->data_buf)); > | > + p->status = USB_RET_STALL; > | > + return; > | > + } > | > | Why this is needed? All control transfers go through do_token_setup > | first, so with the check moved in do_token_setup we should never ever > | trigger it here ... > > usb_handle_packet > -> usb_process_one > -> do_token_in > > Is it possible for a guest to call do_token_in, without calling > do_token_setup first? For anything interesting to happen in do_token_in() setup_state must be set to either ACK or DATA, and for that to be the case do_token_setup() must run first. I don't think the guest can trick qemu to go straight to do_token_in(). Also s->setup_len is set in do_token_setup() only, verifying it once (after setting it from guest-supplied data) should be enough. cheers, Gerd
diff --git a/hw/usb/core.c b/hw/usb/core.c index d0025db..9d90ec7 100644 --- a/hw/usb/core.c +++ b/hw/usb/core.c @@ -128,9 +128,16 @@ static void do_token_setup(USBDevice *s, USBPacket *p) } usb_packet_copy(p, s->setup_buf, p->iov.size); + s->setup_index = 0; p->actual_length = 0; s->setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; - s->setup_index = 0; + if (s->setup_len > sizeof(s->data_buf)) { + fprintf(stderr, + "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", + s->setup_len, sizeof(s->data_buf)); + p->status = USB_RET_STALL; + return; + } request = (s->setup_buf[0] << 8) | s->setup_buf[1]; value = (s->setup_buf[3] << 8) | s->setup_buf[2]; @@ -151,13 +158,6 @@ static void do_token_setup(USBDevice *s, USBPacket *p) } s->setup_state = SETUP_STATE_DATA; } else { - if (s->setup_len > sizeof(s->data_buf)) { - fprintf(stderr, - "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", - s->setup_len, sizeof(s->data_buf)); - p->status = USB_RET_STALL; - return; - } if (s->setup_len == 0) s->setup_state = SETUP_STATE_ACK; else @@ -172,11 +172,18 @@ static void do_token_in(USBDevice *s, USBPacket *p) int request, value, index; assert(p->ep->nr == 0); + if (s->setup_len > sizeof(s->data_buf)) { + fprintf(stderr, + "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", + s->setup_len, sizeof(s->data_buf)); + p->status = USB_RET_STALL; + return; + } request = (s->setup_buf[0] << 8) | s->setup_buf[1]; value = (s->setup_buf[3] << 8) | s->setup_buf[2]; index = (s->setup_buf[5] << 8) | s->setup_buf[4]; - + switch(s->setup_state) { case SETUP_STATE_ACK: if (!(s->setup_buf[0] & USB_DIR_IN)) { diff --git a/hw/usb/dev-network.c b/hw/usb/dev-network.c index 7800cee..ba3c7a7 100644 --- a/hw/usb/dev-network.c +++ b/hw/usb/dev-network.c @@ -914,8 +914,9 @@ static int rndis_query_response(USBNetState *s, bufoffs = le32_to_cpu(buf->InformationBufferOffset) + 8; buflen = le32_to_cpu(buf->InformationBufferLength); - if (bufoffs + buflen > length) + if (buflen > length || bufoffs >= length || bufoffs + buflen > length) { return USB_RET_STALL; + } infobuflen = ndis_query(s, le32_to_cpu(buf->OID), bufoffs + (uint8_t *) buf, buflen, infobuf, @@ -960,8 +961,9 @@ static int rndis_set_response(USBNetState *s, bufoffs = le32_to_cpu(buf->InformationBufferOffset) + 8; buflen = le32_to_cpu(buf->InformationBufferLength); - if (bufoffs + buflen > length) + if (buflen > length || bufoffs >= length || bufoffs + buflen > length) { return USB_RET_STALL; + } ret = ndis_set(s, le32_to_cpu(buf->OID), bufoffs + (uint8_t *) buf, buflen); @@ -1211,8 +1213,9 @@ static void usb_net_handle_dataout(USBNetState *s, USBPacket *p) if (le32_to_cpu(msg->MessageType) == RNDIS_PACKET_MSG) { uint32_t offs = 8 + le32_to_cpu(msg->DataOffset); uint32_t size = le32_to_cpu(msg->DataLength); - if (offs + size <= len) + if (offs < len && size < len && offs + size <= len) { qemu_send_packet(qemu_get_queue(s->nic), s->out_buf + offs, size); + } } s->out_ptr -= len; memmove(s->out_buf, &s->out_buf[len], s->out_ptr);