Re: Executing from dynamically allocated memory

"news" <news@fx32.iad.highwinds-media.com> writes:


> In the past, I've malloc'd memory, written machine instructions into it,
> and called the function I built there.
>
> All this on a 32-bit intel instruction set, on a Debian system.
>
> This appears no longer too work. My program gives a segmentation fault.
> The debugger tells me that the segmentation fault occurs on the first
> instruction of the called function, a
> push %ebp
> residing in malloced memory.
>
> Now it was a year or three ago that this worked. Has Linux changed in
> this respect? Is there something new I have to do to allocate executable
> writable memory for this purpose?
>
> Or might there be something even weirder going on?


It's probably just that anonymous memory is not executable by default
anymore. Take a look at this:


        http://www.akkadia.org/drepper/selinux-mem.html


in particular the execmem case. There is also example code.


SC8ren

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