Hi!
> > . Yes, setarch i386 -R /usr/local/bin/uemacs (etc) fixes them, too.
> >
> > What about this?
> >
> > Heap randomization breaks /lib/libc.so.5.4.33, make it possible to
> > randomize normal stuff but leave the heap alone.
>
> certainly looks fine to me, but please also add a .config to make it
> default to 2. The reason is that a good portions of the overflows happen
> on the heap and 99.9% of the Linux users do not run 1996-era glibc
> anymore.
>
> something like CONFIG_COMPAT_BRK=y, which would cause randomize_va_space
> to default to 1, and if a user or distro disables it, it will default to
> 2.
I named it slightly differently, but idea is same. Heap randomization
breaks ancient binaries, so disable it by default.
Signed-off-by: Pavel Machek <[EMAIL PROTECTED]>
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 18ed6dd..4b099ea 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1077,7 +1077,7 @@ #endif /* ARCH_HAS_SETUP_ADDITIONAL_PAGE
current->mm->start_stack = bprm->p;
#ifdef arch_randomize_brk
- if (current->flags & PF_RANDOMIZE)
+ if ((current->flags & PF_RANDOMIZE) && (randomize_va_space > 1))
current->mm->brk = current->mm->start_brk =
arch_randomize_brk(current->mm);
#endif
diff --git a/init/Kconfig b/init/Kconfig
index dcc96a8..37c7852 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -541,6 +541,16 @@ config ELF_CORE
help
Enable support for generating core dumps. Disabling saves about 4k.
+config RANDOMIZE_HEAP
+ bool "Randomize heap placement"
+ help
+ Randomizing heap placement makes heap exploits harder, but it also
+ breaks old programs (including anything libc5 based). This only
+ changes default, and can be overriden in runtime by tweaking
+ /proc/sys/kernel/randomize_va_space.
+
+ N is safe choice here.
+
config BASE_FULL
default y
bool "Enable full-sized data structures for core" if EMBEDDED
diff --git a/mm/memory.c b/mm/memory.c
index 4706af1..5134014 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -82,7 +82,12 @@ void * high_memory;
EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);
-int randomize_va_space __read_mostly = 1;
+int randomize_va_space __read_mostly =
+#ifdef CONFIG_RANDOMIZE_HEAP
+ 2;
+#else
+ 1;
+#endif
static int __init disable_randmaps(char *s)
{
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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