[ On Friday, March 8, 2002 at 18:21:56 (+0000), xs@kittenz.org wrote: ]
> Subject: Re: FreSSH and bounds checking
>
> gcc-ssp strikes me as a nice fall back in some situations, but
> I don't think it would have helped one bit with this bug,

It may not have helped, but it doesn't hurt either -- I've not noticed
any performance problems with using it on one of the most performance
sensitive applications I run:  Xserver.  (That may be in part due to
better code generation in GCC-2.95.3 vs. EGCS 1.1.2 though.)

> for that
> you would need a malloc implementation that mprotect()'d
> each side of the allocated area, so the program would die if the heap
> overflowed or was accessed,

You mean like what pkgsrc/devel/electricfence can do?

> but this is very inefficient and not so
> portable and might fail too. (I think it would add 8192 bytes to each
> malloc on i386.)

I don't find ElectricFence too big a pig, though it is slower for sure.

There's also the excellent debugging in Phong Vo's vmalloc, which
unfortunately does not yet have a pkgsrc module, which even with full
run-time debugging enabled isn't noticably slower in most applications.

Gray Watson's Debug Malloc library is also very efficient and has caught
a number of bugs in programs I've maintained over the years.

-- 
								Greg A. Woods

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