So I'm wrestling with a particularly nasty bug which is extremely hard to track down. Our hyperspace system completely replaces regular jump gates and holes and relies on forced system switching to work.

In the majority of the cases, the entire thing works fine, but for certain players the game crashes when the system is switched. I've tried tracking it down, but couldn't find anything conclusive.

The only thing I have is a bunch of dumps from after the actual problem which arise on every frame render. The error is:

Unhandled exception at 0x063456F8 (common.dll) in fwtow_06.01.2016_21.32.59-1.dmp: 0xC0000005: Access violation reading location 0x000000FC.

Tracing that down, I find a pretty short piece of code which seems to be involved in getting the ship's center of mass. Since the only ship in hyperspace is the player's, I'm assuming that that is the ship being handled. Looking at the particular line, edx is 0 and it's set as ecx + 0x18.

I don't know what ecx is though (it probably is the CObject?) and I have no information as to what's at 0x18 since the dump doesn't include that memory.

This sounds like information is being corrupted, but the fact it's a null pointer instead of, say, an invalid floating point value, makes me puzzled.

Any ideas?

Hm the exception offset seems to be:



There are various stack traces when i set this breakpoint. But most are related to:



As usual the BaseWatcher::set_pointer
The set_pointer takes a Watchable struct pointer which could be everything. However when i try to get the symbol for that pointer then it is



As GetRadious takes an CObject pointer and a reference to a Vector (and a bool which doesnt play a role i guess) one of both seems to be null. As a reference cannot be null i assume its the CObject.

I am not sure whether this is of any useful information. I would assume its a timing issue, where for some players something is not yet constructed or destroyed or something like this.