Re: static char overflow

[Shaun Clowes <shaun () securereality com au>]

> This has to be the case, since .dtors is always initialized. Initialized
> data cannot be put after the end of p_filesz within that segment.
>
> Mhh... if one is very odd he can construct a valid ELF file with three
> segments that has the .dtors section after the .bss section in memory, but
> no linker will do that on its own ;)

Incidentally this is one of the worst and best features of ELF, the 
specification is very flexible and valid ELF files can be constructed in 
all sorts of ways but the ELF loaders usually only cater for the simplest. 
While an executable could easily be created with any number of 'bss' 
sections at the end of segments it wouldn't actually work on some operating 
systems, in particular the Linux ELF loader (in all the versions I've seen) 
allows only one bss which must be at the end of the address space mapped in 
the segments, if you create a segment following a segment with a bss on the 
end the bss space is not actually allocated and accesses on it will segfault.

Cheers,
Shaun