The patch titled
Subject: arm: mm: support ARCH_MMAP_RND_BITS
has been removed from the -mm tree. Its filename was
arm-mm-support-arch_mmap_rnd_bits.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Daniel Cashman <dcashman@xxxxxxxxxx>
Subject: arm: mm: support ARCH_MMAP_RND_BITS
arm: arch_mmap_rnd() uses a hard-code value of 8 to generate the random
offset for the mmap base address. This value represents a compromise
between increased ASLR effectiveness and avoiding address-space
fragmentation. Replace it with a Kconfig option, which is sensibly
bounded, so that platform developers may choose where to place this
compromise. Keep 8 as the minimum acceptable value.
[arnd@xxxxxxxx: ARM: avoid ARCH_MMAP_RND_BITS for NOMMU]
Signed-off-by: Daniel Cashman <dcashman@xxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Heinrich Schuchardt <xypron.glpk@xxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Mark Salyzyn <salyzyn@xxxxxxxxxxx>
Cc: Jeff Vander Stoep <jeffv@xxxxxxxxxx>
Cc: Nick Kralevich <nnk@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Hector Marco-Gisbert <hecmargi@xxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm/Kconfig | 9 +++++++++
arch/arm/mm/mmap.c | 3 +--
2 files changed, 10 insertions(+), 2 deletions(-)
diff -puN arch/arm/Kconfig~arm-mm-support-arch_mmap_rnd_bits arch/arm/Kconfig
--- a/arch/arm/Kconfig~arm-mm-support-arch_mmap_rnd_bits
+++ a/arch/arm/Kconfig
@@ -37,6 +37,7 @@ config ARM
select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
+ select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_SECCOMP_FILTER if (AEABI && !OABI_COMPAT)
select HAVE_ARCH_TRACEHOOK
select HAVE_ARM_SMCCC if CPU_V7
@@ -311,6 +312,14 @@ config MMU
Select if you want MMU-based virtualised addressing space
support by paged memory management. If unsure, say 'Y'.
+config ARCH_MMAP_RND_BITS_MIN
+ default 8
+
+config ARCH_MMAP_RND_BITS_MAX
+ default 14 if PAGE_OFFSET=0x40000000
+ default 15 if PAGE_OFFSET=0x80000000
+ default 16
+
#
# The "ARM system type" choice list is ordered alphabetically by option
# text. Please add new entries in the option alphabetic order.
diff -puN arch/arm/mm/mmap.c~arm-mm-support-arch_mmap_rnd_bits arch/arm/mm/mmap.c
--- a/arch/arm/mm/mmap.c~arm-mm-support-arch_mmap_rnd_bits
+++ a/arch/arm/mm/mmap.c
@@ -173,8 +173,7 @@ unsigned long arch_mmap_rnd(void)
{
unsigned long rnd;
- /* 8 bits of randomness in 20 address space bits */
- rnd = (unsigned long)get_random_int() % (1 << 8);
+ rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1);
return rnd << PAGE_SHIFT;
}
_
Patches currently in -mm which might be from dcashman@xxxxxxxxxx are
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