trengri commented on a change in pull request #274:
URL: https://github.com/apache/guacamole-server/pull/274#discussion_r419534959
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File path: src/protocols/rdp/channels/rdpsnd/rdpsnd.c
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@@ -35,11 +35,23 @@ void guac_rdpsnd_process_receive(guac_rdp_common_svc* svc,
guac_rdpsnd* rdpsnd = (guac_rdpsnd*) svc->data;
guac_rdpsnd_pdu_header header;
+ /* Check that we at least have a header. */
+ if (Stream_GetRemainingLength(input_stream) < 4)
+ return;
+
/* Read RDPSND PDU header */
Stream_Read_UINT8(input_stream, header.message_type);
Stream_Seek_UINT8(input_stream);
Stream_Read_UINT16(input_stream, header.body_size);
-
+
+ if (Stream_GetRemainingLength(input_stream) < header.body_size) {
+ guac_client_log(svc->client, GUAC_LOG_DEBUG, "Not enough bytes in
stream."
+ " Remaining: %d, Body size: %d",
+ Stream_GetRemainingLength(input_stream),
+ header.body_size);
+ return;
+ }
Review comment:
I'm not a RDP expert. It's just a guess, based on reading the comments
in the source code.
It looks like some PDUs like do not have headers, so there is little sense
in inspecting header.body_size for them...
Maybe you need to move this check a few lines lower (i.e. put it after the
following piece of code)?
https://github.com/apache/guacamole-server/blob/9c37fc56171d55b8fa838949d7fd40db85506857/src/protocols/rdp/channels/rdpsnd/rdpsnd.c#L43-L50
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