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From: Prasad J Pandit <address@hidden>
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When processing remote NDIS control message packets,
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the USB Net device emulator uses a fixed length(4096) data buffer.
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The incoming informationBufferOffset & Length combination could
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overflow and cross that range. Check control message buffer
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offsets and length to avoid it.
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Reported-by: Qinghao Tang <address@hidden>
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Signed-off-by: Prasad J Pandit <address@hidden>
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---
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 hw/usb/dev-network.c | 9 ++++++---
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 1 file changed, 6 insertions(+), 3 deletions(-)
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Update as per review
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  -> https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg03475.html
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diff --git a/hw/usb/dev-network.c b/hw/usb/dev-network.c
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index 8a4ff49..180adce 100644
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--- a/tools/qemu-xen/hw/usb/dev-network.c
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+++ b/tools/qemu-xen/hw/usb/dev-network.c
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@@ -915,8 +915,9 @@ static int rndis_query_response(USBNetState *s,
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     bufoffs = le32_to_cpu(buf->InformationBufferOffset) + 8;
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     buflen = le32_to_cpu(buf->InformationBufferLength);
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-    if (bufoffs + buflen > length)
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+    if (buflen > length || bufoffs >= length || bufoffs + buflen > length) {
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         return USB_RET_STALL;
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+    }
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     infobuflen = ndis_query(s, le32_to_cpu(buf->OID),
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                             bufoffs + (uint8_t *) buf, buflen, infobuf,
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@@ -961,8 +962,9 @@ static int rndis_set_response(USBNetState *s,
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     bufoffs = le32_to_cpu(buf->InformationBufferOffset) + 8;
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     buflen = le32_to_cpu(buf->InformationBufferLength);
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-    if (bufoffs + buflen > length)
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+    if (buflen > length || bufoffs >= length || bufoffs + buflen > length) {
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         return USB_RET_STALL;
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+    }
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     ret = ndis_set(s, le32_to_cpu(buf->OID),
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                     bufoffs + (uint8_t *) buf, buflen);
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@@ -1212,8 +1214,9 @@ static void usb_net_handle_dataout(USBNetState *s, USBPacket *p)
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     if (le32_to_cpu(msg->MessageType) == RNDIS_PACKET_MSG) {
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         uint32_t offs = 8 + le32_to_cpu(msg->DataOffset);
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         uint32_t size = le32_to_cpu(msg->DataLength);
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-        if (offs + size <= len)
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+        if (offs < len && size < len && offs + size <= len) {
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             qemu_send_packet(qemu_get_queue(s->nic), s->out_buf + offs, size);
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+        }
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     }
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     s->out_ptr -= len;
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     memmove(s->out_buf, &s->out_buf[len], s->out_ptr);
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-- 
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2.5.0