From: Jiri Kosina Date: Sat, 9 Feb 2008 22:24:08 +0000 (+0100) Subject: brk: document randomize_va_space and CONFIG_COMPAT_BRK (was Re: X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=1ec7fd50ba4f845d1cf6b67acabd774577ef13b6;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git brk: document randomize_va_space and CONFIG_COMPAT_BRK (was Re: Document randomize_va_space and CONFIG_COMPAT_BRK. Signed-off-by: Jiri Kosina Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 8984a5396271..dc8801d4e944 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -41,6 +41,7 @@ show up in /proc/sys/kernel: - pid_max - powersave-nap [ PPC only ] - printk +- randomize_va_space - real-root-dev ==> Documentation/initrd.txt - reboot-cmd [ SPARC only ] - rtsig-max @@ -280,6 +281,34 @@ send before ratelimiting kicks in. ============================================================== +randomize-va-space: + +This option can be used to select the type of process address +space randomization that is used in the system, for architectures +that support this feature. + +0 - Turn the process address space randomization off by default. + +1 - Make the addresses of mmap base, stack and VDSO page randomized. + This, among other things, implies that shared libraries will be + loaded to random addresses. Also for PIE-linked binaries, the location + of code start is randomized. + + With heap randomization, the situation is a little bit more + complicated. + There a few legacy applications out there (such as some ancient + versions of libc.so.5 from 1996) that assume that brk area starts + just after the end of the code+bss. These applications break when + start of the brk area is randomized. There are however no known + non-legacy applications that would be broken this way, so for most + systems it is safe to choose full randomization. However there is + a CONFIG_COMPAT_BRK option for systems with ancient and/or broken + binaries, that makes heap non-randomized, but keeps all other + parts of process address space randomized if randomize_va_space + sysctl is turned on. + +============================================================== + reboot-cmd: (Sparc only) ??? This seems to be a way to give an argument to the Sparc