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authorLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:51:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:51:45 -0700
commit342ff1a1b558ebbdb8cbd55ab6a63eca8b2473ca (patch)
tree1f967f283dade6e03897169bb29513354f49f910 /Documentation/sysctl
parent50223e486cabdcf7e540e519da1f26bab3084e5d (diff)
parent24ed7a97464db44592495f98cff8bcee02f92bc2 (diff)
downloadlinaro-lsk-342ff1a1b558ebbdb8cbd55ab6a63eca8b2473ca.tar.gz
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (34 commits) trivial: fix typo in aic7xxx comment trivial: fix comment typo in drivers/ata/pata_hpt37x.c trivial: typo in kernel-parameters.txt trivial: fix typo in tracing documentation trivial: add __init/__exit macros in drivers/gpio/bt8xxgpio.c trivial: add __init macro/ fix of __exit macro location in ipmi_poweroff.c trivial: remove unnecessary semicolons trivial: Fix duplicated word "options" in comment trivial: kbuild: remove extraneous blank line after declaration of usage() trivial: improve help text for mm debug config options trivial: doc: hpfall: accept disk device to unload as argument trivial: doc: hpfall: reduce risk that hpfall can do harm trivial: SubmittingPatches: Fix reference to renumbered step trivial: fix typos "man[ae]g?ment" -> "management" trivial: media/video/cx88: add __init/__exit macros to cx88 drivers trivial: fix typo in CONFIG_DEBUG_FS in gcov doc trivial: fix missing printk space in amd_k7_smp_check trivial: fix typo s/ketymap/keymap/ in comment trivial: fix typo "to to" in multiple files trivial: fix typos in comments s/DGBU/DBGU/ ...
Diffstat (limited to 'Documentation/sysctl')
-rw-r--r--Documentation/sysctl/kernel.txt30
1 files changed, 17 insertions, 13 deletions
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 2dbff53369d..3e5b63ebb82 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -319,25 +319,29 @@ 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.
+0 - Turn the process address space randomization off. This is the
+ default for architectures that do not support this feature anyways,
+ and kernels that are booted with the "norandmaps" parameter.
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.
+ loaded to random addresses. Also for PIE-linked binaries, the
+ location of code start is randomized. This is the default if the
+ CONFIG_COMPAT_BRK option is enabled.
- With heap randomization, the situation is a little bit more
- complicated.
- There a few legacy applications out there (such as some ancient
+2 - Additionally enable heap randomization. This is the default if
+ CONFIG_COMPAT_BRK is disabled.
+
+ There are 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
+ 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.
+ systems it is safe to choose full randomization.
+
+ Systems with ancient and/or broken binaries should be configured
+ with CONFIG_COMPAT_BRK enabled, which excludes the heap from process
+ address space randomization.
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