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| author | Jiri Kosina <jkosina@suse.cz> | 2008-02-09 23:24:08 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2008-02-09 23:24:08 +0100 |
| commit | 1ec7fd50ba4f845d1cf6b67acabd774577ef13b6 (patch) | |
| tree | 267a1c61fa9a324c90ac8b59203e9bc1087f7dc7 /Documentation/sysctl/kernel.txt | |
| parent | 6697c05296fab4d113c7144459b72b6172b485a5 (diff) | |
| download | lwn-1ec7fd50ba4f845d1cf6b67acabd774577ef13b6.tar.gz lwn-1ec7fd50ba4f845d1cf6b67acabd774577ef13b6.zip | |
brk: document randomize_va_space and CONFIG_COMPAT_BRK (was Re:
Document randomize_va_space and CONFIG_COMPAT_BRK.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/sysctl/kernel.txt')
| -rw-r--r-- | Documentation/sysctl/kernel.txt | 29 |
1 files changed, 29 insertions, 0 deletions
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 |