Dopus 10 crashes due to bug in UltraCompare

Just a startup topic to tell you i got minidumps for a crash happening in dopus_main when i start UltraCompare on my computer. Every time, it crashes. I can provides minidumps here : jbriguet.com/jb/DOpus.Minidumps/, during this time, i'll do the analyze steps described here : General slowdown or instability investigation steps

Regards,

JB

I can confirm the crash, however the bug is in UltraCompare.

Whenever UltraCompare starts it is sending several broadcast window messages to every single program on the desktop. The messages are in the WM_APP range, which means they have a different meaning to every application. (In Opus's case, receiving one of them makes it crash. It could cause any app to do anything.)

What UltraCompare is doing is completely illegal. Programs must not send messages in that range to unknown windows and especially must not broadcast them to all windows/applications. If they really must broadcast a message to every window (why??) then they should allocate one using RegisterWindowMessage, which will ensure the message does not conflict with any other.

Here is an example showing a test-app I am working on, and a log of the messages it receives. The test-app was not in use when I launched UltraCompare. As you can see, the test-app received multiple messages in the WM_APP range.

For all UltaCompare knows, one of those window messages could mean "format the hard-drive" to an application, so what it's doing is very dangerous.


PS: While the bug is in UC, we'll put a workaround into the next Opus update to prevent the crash, in case they do not fix it. I would avoid running UC until they have fixed the bug, though, as there's no way to know what that message will mean to other applications.

Thanks a lot for that :slight_smile: I know the faulty behavior comes from UltraCompare, and while i rarely use it, i use Dopus everyday, and it is the one which is crashing. A fix is always welcome. Thanks again :slight_smile:
(Btw, i tried everything in the investigation steps anyway, and some might be outdated)

Have you reported this bug to the authors of UltraCompare?

Yep, i did it, and i got answered this :

[quote]Hello JB,

Thank you for your message and for pointing this out. We have had
another user report this and our developers are investigating this. We
will be sure to let you know when we have an updated build that we
believe corrects this issue.

Thanks, Troy
[/quote]

Nice to see professionalism on both sides :slight_smile:

The 10.0.0.1 beta (in the Illuminati forum) has a workaround for the bug in UltraCompare that prevents the crash.
(it's still something UltraCompare need to fix, however).

I received a message a few days ago from UltraCompare Team, they have published a new version not broadcasting anymore messages. I checked, it does not crash Dopus anymore \o/

Good to know! Solved on both sides. :slight_smile: