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-   -   Bug: Bug Thread: Discussion (http://forum.shrapnelgames.com/showthread.php?t=30593)

JimMorrison December 1st, 2008 03:11 PM

Re: Bug Thread: Discussion
 
Quote:

Originally Posted by lch (Post 656601)
Quote:

Originally Posted by Loren (Post 656572)
I've been playing with the Vampiri mod race and three times now during turn generation Dominions has vanished. Loading it up and hitting End Turn always works, though.

"Vanished" is not a useful error report. The game gives an error message when it crashes, you should copy and paste that to determine the kind of problem there is.

It's only not useful if it's not clarified in any way. But Dominions still has the "CTD during turn resolution" problem sometimes, and when that occurs, it just dumps you to desktop without any fanfare or explanation. It certainly sounds like that is what Loren is reporting (I think it was listed in the patch notes as fixed in 3.21, but I can confirm seeing it since then as well).

Loren December 1st, 2008 03:38 PM

Re: Bug Thread: Discussion
 
Quote:

Originally Posted by lch (Post 656601)
Quote:

Originally Posted by Loren (Post 656572)
I've been playing with the Vampiri mod race and three times now during turn generation Dominions has vanished. Loading it up and hitting End Turn always works, though.

"Vanished" is not a useful error report. The game gives an error message when it crashes, you should copy and paste that to determine the kind of problem there is.

I mean vanished. No error message. One instant it's there, the next it's gone. I've never seen exactly what phase of the turn generation it's on when it happens.

This probably means a stack overflow.

Loren December 1st, 2008 03:39 PM

Re: Bug Thread: Discussion
 
Quote:

Originally Posted by JimMorrison (Post 656677)
Quote:

Originally Posted by lch (Post 656601)
Quote:

Originally Posted by Loren (Post 656572)
I've been playing with the Vampiri mod race and three times now during turn generation Dominions has vanished. Loading it up and hitting End Turn always works, though.

"Vanished" is not a useful error report. The game gives an error message when it crashes, you should copy and paste that to determine the kind of problem there is.

It's only not useful if it's not clarified in any way. But Dominions still has the "CTD during turn resolution" problem sometimes, and when that occurs, it just dumps you to desktop without any fanfare or explanation. It certainly sounds like that is what Loren is reporting (I think it was listed in the patch notes as fixed in 3.21, but I can confirm seeing it since then as well).

This sounds exactly like what I'm seeing.

vfb December 1st, 2008 08:25 PM

Re: Bug Thread: Discussion
 
In-game messages like "I'm setting taxes to 0% so you go bankrupt" can cause the turn to crash when they are viewed.

The game formats messages that are displayed on the screen using one of the printf calls. It should pass ( ..., "%s", message ) for user-entered messages. But instead it passes ( ..., message ). So if 'message' contains printf formatting, it will expect additional arguments. And if the printf code is '%s' (spaces between the '%' and 's' don't matter), it will treat whatever happens to be on the stack as an address to read a string from. If this address is invalid, that can cause a crash.

Soyweiser December 2nd, 2008 08:21 AM

Re: Bug Thread: Discussion
 
Quote:

Originally Posted by vfb (Post 656736)
In-game messages like "I'm setting taxes to 0% so you go bankrupt" can cause the turn to crash when they are viewed.

The game formats messages that are displayed on the screen using one of the printf calls. It should pass ( ..., "%s", message ) for user-entered messages. But instead it passes ( ..., message ). So if 'message' contains printf formatting, it will expect additional arguments. And if the printf code is '%s' (spaces between the '%' and 's' don't matter), it will treat whatever happens to be on the stack as an address to read a string from. If this address is invalid, that can cause a crash.

This is a serious problem. This can cause much more than a simple crash. If someone makes a malicious message, it could take over your computer.

http://en.wikipedia.org/wiki/Format_string_attack

MaxWilson December 2nd, 2008 07:26 PM

Re: Bug Thread: Discussion
 
Oh, wow. %n does not modify the output from printf but instead treats its arguments are a memory address and sets it to the number of characters printed so far. That raises the threat potential from printing out the contents of your Dom3 process to modifying memory, including the instruction pointer. http://julianor.tripod.com/bc/formatstring-1.2.pdf

It's interesting that vfb reports that this will cause crashes. Maybe Dom3 is compiled in a mode that does stricter checking of printf, and throws an exception if the wrong number of arguments is supplied. In that case it's not a security threat after all.

-Max

vfb December 2nd, 2008 07:53 PM

Re: Bug Thread: Discussion
 
Quote:

Originally Posted by MaxWilson (Post 656932)
Oh, wow. %n does not modify the output from printf but instead treats its arguments are a memory address and sets it to the number of characters printed so far. That raises the threat potential from printing out the contents of your Dom3 process to modifying memory, including the instruction pointer. http://julianor.tripod.com/bc/formatstring-1.2.pdf

It's interesting that vfb reports that this will cause crashes. Maybe Dom3 is compiled in a mode that does stricter checking of printf, and throws an exception if the wrong number of arguments is supplied. In that case it's not a security threat after all.

-Max

No, I just said %s will cause crashes. I did not think of %n, I was not aware of that actually.

The printf call used does check for a null argument to %s on the stack and prints "(null)" in that case, but it's going to seg fault (crash) if there's something on the stack like a random integer value.

It's impossible to do a compile-time check of the printf arg count when the format string itself is variable. And that's the problem here, the format string should be "%s" instead of the user-entered message.

It's also impossible for a library function like printf to know how many arguments it was actually passed. Whatever is on the stack is just there, and it will try to use it according to the format string.

lch December 3rd, 2008 07:58 AM

Re: Bug Thread: Discussion
 
Black Laurel, Ivy Crown and Crown of the Ivy King do not provide an armor to the wearer, bug or WAD? I remember that a couple of crowns were missing their armor, and KO said something like "remind me of any other crowns like this".

Tifone December 3rd, 2008 08:00 AM

Re: Bug Thread: Discussion
 
Should they provide armor? They're leaves after all :)

Dectilon December 4th, 2008 04:27 PM

Re: Bug Thread: Discussion
 
I don't know if this has been mentioned but:

If I use the random map generator once, quit that game and generate a new map I get the exact same map grahpics but with each province redefined (water provinces will often be land and vice versa).


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