[Spice-devel] [vdagent-win PATCH v4 03/19] Minor overflow checks improvements

[Frediano Ziglio]

Although source of these data should be safe, improve data checks
to avoid some overflows and make the code more robust.

Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
Acked-by: Jonathon Jongsma <jjongsma at redhat.com>
---
 vdagent/vdagent.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/vdagent/vdagent.cpp b/vdagent/vdagent.cpp
index cf492cc..9fbff3d 100644
--- a/vdagent/vdagent.cpp
+++ b/vdagent/vdagent.cpp
@@ -1368,7 +1368,7 @@ VOID VDAgent::read_completion(DWORD err, DWORD bytes, LPOVERLAPPED overlapped)
         count = sizeof(VDIChunk) - a->_read_pos;
     } else if (a->_read_pos == sizeof(VDIChunk)) {
         count = chunk->hdr.size;
-        if (a->_read_pos + count > sizeof(a->_read_buf)) {
+        if (count > sizeof(a->_read_buf) - a->_read_pos) {
             vd_printf("chunk is too large, size %u port %u", chunk->hdr.size, chunk->hdr.port);
             a->_running = false;
             return;
@@ -1420,6 +1420,12 @@ void VDAgent::handle_chunk(VDIChunk* chunk)
     }
 
     // the previous chunk was a partial message, so append this chunk to the previous chunk
+    if (chunk->hdr.size > sizeof(VDAgentMessage) + _in_msg->size - _in_msg_pos) {
+        vd_printf("Invalid VDAgentMessage message");
+        _running = false;
+        return;
+    }
+
     memcpy((uint8_t*)_in_msg + _in_msg_pos, chunk->data, chunk->hdr.size);
     _in_msg_pos += chunk->hdr.size;
     // update clipboard tick on each clipboard chunk for timeout setting
-- 
2.17.1