On 3 Apr 2009 at 1:22, Alex Efros wrote: > On Thu, Apr 02, 2009 at 11:17:10PM +0200, pagee...@freemail.hu wrote: > > can you strace bash/etc to see what happens? probably we'll see what runs > > how do I can strace process N1?
you can enable and boot into softmode then turn it off and see what you can reproduce then. that won't let you strace pid=1 but let's you play with the rest while running an MPROTECT kernel. > PaX doesn't kill bash if it executed not as process N1. hmm, i don't get it. are you saying that with MPROTECT enabled in the kernel, bash fails to start when run as init, but works otherwise? > > against the MPROTECT restricions. my guess is either textrels or gnu_stack > > (compare scanelf -lpqRte on your systems). > > it's same on all servers: hmm, so nothing stands out, and only pid=1 is ever affected? i've never seen such a failure mode ;). > > btw, why are you using SEGMEXEC on your core2? > > Hmm. You think I should use PAGEEXEC instead? According to help in linux > kernel SEGMEXEC looks more suitable for Core2Duo and Xeon E5310... > > In help for PAGEEXEC it doesn't recommended for P4 and there is nothing > about newest processors, so I suppose PAGEEXEC may not be a good choice. the help talks about exactly what is problematic, the P4 core. the core2 is different, and it also has hw non-exec support. > After your question I've re-read help, and notice "i386 with hardware > non-executable bit support" item at end of list with less usual archs like > avr32, sparc, etc. If that was said about Core/Xeon too, then there > probably little usability issue with that help. ;-) i can't possibly list every cpuid that has NX support, up to you to determine it ;). besides, you can always enable both non-exec features and the kernel will choose the better one at runtime.
