Hi!
> > Hmm, code in binfmt_elf is really strange.
> >
> > elf_bss += load_bias;
> > elf_brk += load_bias;
> > start_code += load_bias;
> > end_code += load_bias;
> > start_data += load_bias;
> > end_data += load_bias;
> >
> > /* Calling set_brk effectively mmaps the pages that we need
> > * for the bss and break sections. We must do this before
> > * mapping in the interpreter, to make sure it doesn't wind
> > * up getting placed where the bss needs to go.
> > */
> > retval = set_brk(elf_bss, elf_brk);
> >
> > ... so we allocate non-randoimzed brk, but later we just overwrite bss
> > variable with new, shiner and better randomized value... without
> > unmapping the old one... The code in binfmt_elf.c is really a mess.
>
> hm, so it seems that it isnt even the randomization that causes the
> problem - but somehow the randomization code itself is broken, right?
>
> Would you be interested in figuring out how to unbreak this? [if not,
> could you send me the binary?]
Not sure this helps... If I only randomize _end_ of heap, it still
works. If I try to randomize beggining of heap, too, it will not even
start recent binaries :-(.
Pavel
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 18ed6dd..9afc58f 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -980,6 +983,16 @@ #endif
}
loc->elf_ex.e_entry += load_bias;
+
+
+ printk("%d: %x\n", current->pid, elf_brk);
+
+ extern unsigned long randomize_range(unsigned long start, unsigned
long end, unsigned long len);
+
+ long random = randomize_range(0, 0x200000, 0);
+ elf_brk += random;
+// elf_bss += random;
+
elf_bss += load_bias;
elf_brk += load_bias;
start_code += load_bias;
@@ -1076,12 +1093,6 @@ #endif /* ARCH_HAS_SETUP_ADDITIONAL_PAGE
current->mm->end_data = end_data;
current->mm->start_stack = bprm->p;
-#ifdef arch_randomize_brk
- if (current->flags & PF_RANDOMIZE)
- current->mm->brk = current->mm->start_brk =
- arch_randomize_brk(current->mm);
-#endif
-
if (current->personality & MMAP_PAGE_ZERO) {
/* Why this, you ask??? Well SVr4 maps page 0 as read-only,
and some applications "depend" upon this behavior.
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
