Odd segfault in nagios.

[Steven D. Morrey]

Hi Everyone,

I've been working on making some improvements to DNX.
I believe I've stumbled on an error in nagios.  It's an issue in 2.7 which is what we use here, but it may be an issue in later versions as well, since I don't see anywhere steps have been taken to prevent it.
In utils.c on line 3834 there is this line.
memcpy(message,((service_message **)service_result_buffer.buffer)[service_result_buffer.tail],sizeof(service_message));

It's purpose is to copy a message from the service result buffer to the "message"  buffer.

The problem arises in instances where the message that the service result buffer contains is null or empty.
Now while I'm not exactly sure how this situation arose (probably DNX posted something weird), but the fact that it's segfaulting here if the message is null or empty, that seems to me to be a bit of a bug.
The solution is obviously to check that we have valid data before performing the memcpy operation.

I've created a patch that fixes this, and I'll get it up for the 2.x branch once it's tested, and if anyone can confirm that this bug is present in Nagios 3x I'll get a patch going for it as well.

Thanks for taking a moment to read this.

Sincerely,
Steve 


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