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Crash of mosquitto broker on Windows when client disconnects from websocket connection #1137

krismattheus opened this Issue Feb 1, 2019 · 1 comment


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krismattheus commented Feb 1, 2019

There is a bug in the callback_mqtt function in websockets.c, that causes a crash of the mosquitto broker on Windows when a client closes its websocket connection.

if(mosq->sock > 0){
should be changed to:

if((int)mosq->sock > 0){
if(mosq->sock != INVALID_SOCKET){

A socket on Windows is an unsigned int, so this test succeeds even when the value is INVALID_SOCKET.
This invalid test causes the HASH_DELETE to be called again when the socket is already closed. This causes the crash. After changing the code the crash no longer happens.

Some extra info:
We use mosquitto version 1.5.5 and libwebsockets 3.0.1

@ralight ralight added this to the 1.5.6 milestone Feb 2, 2019


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ralight commented Feb 2, 2019

Thanks, that's fixed in my local branch and will be pushed as part of 1.5.6 shortly.

@ralight ralight closed this Feb 2, 2019

ralight added a commit that referenced this issue Feb 8, 2019

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