per page execute

Alan Modra amodra at
Wed Dec 31 09:18:41 EST 2003

On Sat, Dec 27, 2003 at 11:15:25PM +1100, Anton Blanchard wrote:
>   [25] .plt NOBITS 10010c08 000c00 0000c0 00 WAX 0   0  4
>   [26] .bss NOBITS 10010cc8 000c00 000004 00  WA 0   0  1
> Look how the non executable bss butts right onto the executable plt.
> Even with the patch below, we are failing some security tests that try
> and exec stuff out of the bss. Thats because the stuff ends up in the same
> page as the plt. Alan, could this be considered a toolchain bug?

Possibly.  What about .got (exec) and adjacent .sdata (non-exec)?  The
ABI says that shared libs access .sdata via the got pointer, so
there's no hope of separating them.

Alan Modra
IBM OzLabs - Linux Technology Centre

** Sent via the linuxppc64-dev mail list. See

More information about the Linuxppc64-dev mailing list