[PATCH] Kconfig: enhance DEFAULT_MMAP_MIN_ADDR description

[PATCH] Kconfig: enhance DEFAULT_MMAP_MIN_ADDR description

[maximilian attems]

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.

Signed-off-by: maximilian attems <max@stro.at>
Cc: Martin Michlmayr <tbm@cyrius.com>
Cc: Gordon Farquharson <gordonfarquharson@gmail.com>
---
 security/Kconfig |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/security/Kconfig b/security/Kconfig
index 5dfc206..cc1e4bd 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -113,8 +113,9 @@ 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
+	  For most 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.
 
-- 
1.5.5

Re: [PATCH] Kconfig: enhance DEFAULT_MMAP_MIN_ADDR description

[Eric Paris]

On Wed, 2008-04-16 at 19:13 +0200, maximilian attems wrote:
> 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.

I certainly don't have a problem with the patch.

Acked-by: Eric Paris <eparis@redhat.com>

Although I do have reports of ppc64 and ia64 working fine with 64k I
don't see the need to clutter up the issue by listing all 3 arches I've
seen it not break instead of your message just mentioning x86.

-Eric

Re: [PATCH] Kconfig: enhance DEFAULT_MMAP_MIN_ADDR description

[maximilian attems]

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>

diff --git a/security/Kconfig b/security/Kconfig
index 5dfc206..49b51f9 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -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.

Re: [PATCH] Kconfig: enhance DEFAULT_MMAP_MIN_ADDR description

[James Morris]

On Wed, 16 Apr 2008, maximilian attems wrote:

> 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>

Applied to 
git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/selinux-2.6.git#for-akpm


-- 
James Morris
<jmorris@namei.org>