The patch titled
Subject: arm64-mm-support-arch_mmap_rnd_bits-v4
has been added to the -mm tree. Its filename is
arm64-mm-support-arch_mmap_rnd_bits-v4.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/arm64-mm-support-arch_mmap_rnd_bits-v4.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/arm64-mm-support-arch_mmap_rnd_bits-v4.patch
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------------------------------------------------------
From: Daniel Cashman <dcashman@xxxxxxxxxxx>
Subject: arm64-mm-support-arch_mmap_rnd_bits-v4
arm64: arch_mmap_rnd() uses STACK_RND_MASK 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 default values as new minimums.
Signed-off-by: Daniel Cashman <dcashman@xxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/Kconfig | 20 ++++++++++++++------
arch/arm64/mm/mmap.c | 2 ++
2 files changed, 16 insertions(+), 6 deletions(-)
diff -puN arch/arm64/Kconfig~arm64-mm-support-arch_mmap_rnd_bits-v4 arch/arm64/Kconfig
--- a/arch/arm64/Kconfig~arm64-mm-support-arch_mmap_rnd_bits-v4
+++ a/arch/arm64/Kconfig
@@ -108,20 +108,28 @@ config MMU
config ARCH_MMAP_RND_BITS_MIN
default 15 if ARM64_64K_PAGES
+ default 17 if ARM64_16K_PAGES
default 19
config ARCH_MMAP_RND_BITS_MAX
- default 20 if ARM64_64K_PAGES && ARCH_VA_BITS=39
- default 24 if ARCH_VA_BITS=39
- default 23 if ARM64_64K_PAGES && ARCH_VA_BITS=42
- default 27 if ARCH_VA_BITS=42
- default 29 if ARM64_64K_PAGES && ARCH_VA_BITS=48
- default 33 if ARCH_VA_BITS=48
+ default 19 if ARM64_VA_BITS=36
+ default 20 if ARM64_64K_PAGES && ARM64_VA_BITS=39
+ default 22 if ARM64_16K_PAGES && ARM64_VA_BITS=39
+ default 24 if ARM64_VA_BITS=39
+ default 23 if ARM64_64K_PAGES && ARM64_VA_BITS=42
+ default 25 if ARM64_16K_PAGES && ARM64_VA_BITS=42
+ default 27 if ARM64_VA_BITS=42
+ default 30 if ARM64_VA_BITS=47
+ default 29 if ARM64_64K_PAGES && ARM64_VA_BITS=48
+ default 31 if ARM64_16K_PAGES && ARM64_VA_BITS=48
+ default 33 if ARM64_VA_BITS=48
default 15 if ARM64_64K_PAGES
+ default 17 if ARM64_16K_PAGES
default 19
config ARCH_MMAP_RND_COMPAT_BITS_MIN
default 7 if ARM64_64K_PAGES
+ default 9 if ARM64_16K_PAGES
default 11
config ARCH_MMAP_RND_COMPAT_BITS_MAX
diff -puN arch/arm64/mm/mmap.c~arm64-mm-support-arch_mmap_rnd_bits-v4 arch/arm64/mm/mmap.c
--- a/arch/arm64/mm/mmap.c~arm64-mm-support-arch_mmap_rnd_bits-v4
+++ a/arch/arm64/mm/mmap.c
@@ -51,9 +51,11 @@ unsigned long arch_mmap_rnd(void)
{
unsigned long rnd;
+ifdef CONFIG_COMPAT
if (test_thread_flag(TIF_32BIT))
rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_compat_bits);
else
+#endif
rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_bits);
return rnd << PAGE_SHIFT;
}
_
Patches currently in -mm which might be from dcashman@xxxxxxxxxxx are
mm-mmap-add-new-proc-tunable-for-mmap_base-aslr-v4.patch
arm64-mm-support-arch_mmap_rnd_bits-v4.patch
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