brk randomization: introduce CONFIG_COMPAT_BRK

based on similar patch from: Pavel Machek <pavel@ucw.cz>

Introduce CONFIG_COMPAT_BRK. If disabled then the kernel is free
(but not obliged to) randomize the brk area.

Heap randomization breaks ancient binaries, so we keep COMPAT_BRK
enabled by default.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 0 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 87f50df58893..92b23e256614 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -541,6 +541,18 @@ config ELF_CORE
         help
           Enable support for generating core dumps. Disabling saves about 4k.
 
+config COMPAT_BRK
+        bool "Disable heap randomization"
+        default y
+        help
+          Randomizing heap placement makes heap exploits harder, but it
+          also breaks ancient binaries (including anything libc5 based).
+          This option changes the bootup default to heap randomization
+          disabled, and can be overriden runtime by setting
+          /proc/sys/kernel/randomize_va_space to 2.
+
+          On non-ancient distros (post-2000 ones) Y is usually a safe choice.
+
 config BASE_FULL
         default y
         bool "Enable full-sized data structures for core" if EMBEDDED