Kernel hacking option "Debug memory allocations" possible leak ofPaX memory randomization

From: Lorenzo Hernandez Garcia-Hierro
Date: Tue Jul 13 2004 - 08:53:31 EST


Hi,

I've compiled a new kernel (2.6.7) 2 days ago, using the grSecurity
patch that comes with PaX inside.

I've configured the environment for running with PaX, and i ran out that
PaX tests.

They shown suspicious results:

Anonymous mapping randomisation test : 16 bits (guessed)
Heap randomisation test (ET_EXEC) : 13 bits (guessed)
Heap randomisation test (ET_DYN) : 23 bits (guessed)
Main executable randomisation (ET_EXEC) : No randomisation
Main executable randomisation (ET_DYN) : 15 bits (guessed)
Shared library randomisation test : 15 bits (guessed)
Stack randomisation test (SEGMEXEC) : 23 bits (guessed)
Stack randomisation test (PAGEEXEC) : 23 bits (guessed)

I didn't know why the test shown that but i'm suspecting on the kernel
hacking option called "Debug memory allocations" that it's enabled on my
kernel configuration.

I've talked with Peter Busser from the Adamantix project about it he thinks
that it's possible, i'm not sure and i didn't make a further research on it.

Is anyone of you having the same situation, is it an unexpected behavior or it's a bug
on the kernel source?
Is that option non-compatible with PaX RANDSTACK and the rest of PaX's memory randomization
features?

Cheers,

--
Lorenzo Hernandez Garcia-Hierro <lorenzo@xxxxxxx>

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