security: enhance DEFAULT_MMAP_MIN_ADDR description

Got burned by setting the proposed default of 65536
across all Debian archs.

Thus proposing to be more specific on which archs you may
set this. Also propose a value for arm and friends that
doesn't break sshd.

Reword to mention working archs ia64 and ppc64 too.

Signed-off-by: maximilian attems <max@stro.at>
Cc: Martin Michlmayr <tbm@cyrius.com>
Cc: Gordon Farquharson <gordonfarquharson@gmail.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
maximilian attems 2008-04-16 19:36:36 +02:00 committed by James Morris
parent 27cc2a6e57
commit 5f46ce14bd

View file

@ -113,10 +113,12 @@ config SECURITY_DEFAULT_MMAP_MIN_ADDR
from userspace allocation. Keeping a user from writing to low pages
can help reduce the impact of kernel NULL pointer bugs.
For most users with lots of address space a value of 65536 is
reasonable and should cause no problems. Programs which use vm86
functionality would either need additional permissions from either
the LSM or the capabilities module or have this protection disabled.
For most ia64, ppc64 and x86 users with lots of address space
a value of 65536 is reasonable and should cause no problems.
On arm and other archs it should not be higher than 32768.
Programs which use vm86 functionality would either need additional
permissions from either the LSM or the capabilities module or have
this protection disabled.
This value can be changed after boot using the
/proc/sys/vm/mmap_min_addr tunable.