add -gx to add stack smash code

[WalterBright]

With -gx switch, adds code to smash the local variables upon function exit. Useful for flushing out heisenbugs.

A partial implementation of bug http://d.puremagic.com/issues/show_bug.cgi?id=9242

[alexrp]

Maybe a different name? The term "stack smashing" is usually used in the context of the stack smashing protector that GCC and LLVM support: http://llvm.org/docs/LangRef.html#llvm-stackprotector-intrinsic (see also the ssp, sspreq, and sspstrong attributes in that document)

[WalterBright]

I don't see the word "smash" in the linked page.

[alexrp]

ssp stands for stack smashing protector (http://en.wikipedia.org/wiki/Buffer_overflow_protection#GCC_Stack-Smashing_Protector_.28ProPolice.29)

[yebblies]

Why do you have this disabled for win64?

[yebblies]

Sorry, I'm tried. What I meant to ask was - is this really equivalent to all of the other epilogs? And if so, could they be merged together instead of having a universal stack smash version and several target dependent versions?

[WalterBright]

The other ones are optimal for different purposes, as the if statements set out. The win64 is different because the win64 api says it should be that way, see the supplied url.

[dnadlinger]

I know I've used smashStack as function name in some code snippets I posted on the forums in the past, but when reading about »stack smashing« in connection with compilers, I think about the exploitation technique (as in the seminal »Smashing the Stack for Fun and Profit« paper) and related countermeasures, not a debugging helper.

So maybe »overwrite stack with garbage when returning from a function« or something along the lines would be a better description for a flag? A reference to »stack smashing code« would probably need further explanation in the (non-existent?) docs, unless you are building an exploit kit. ;)

[leandro-lucarella-sociomantic]

On Thu, Jan 24, 2013 at 05:53:28AM -0800, David Nadlinger wrote:

I know I've used smashStack as function name in some code snippets I posted on the forums in the past, but still when reading about »stack smashing« in connection with compilers, I think about the exploitation technique (as in the seminal »Smashing the Stack for Fun and Profit« paper) and related countermeasures, not a debugging helper.

So maybe »overwrite stack with garbage when returning from a function« or something along the lines would be a better description for a flag? A reference to »stack smashing code« would probably need further explanation in the (non-existent?) docs, unless you are building an exploit kit. ;)

A similar technique is (optionally) used in the GC to debug memory
problems, and is called "memory stomping", so maybe "stack stomping"
could be used instead to maintain some consistency...

https://github.com/D-Programming-Language/druntime/blob/master/src/gc/gcx.d#L23

[WalterBright]

stomping sounds good

[leandro-lucarella-sociomantic]

Haha, it looks like you're using smashing in the code after all :P