diff options
| author | Matt Redfearn <matt.redfearn@imgtec.com> | 2016-11-24 17:32:45 +0000 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2017-01-03 16:34:43 +0100 |
| commit | 109c32ffd89d64dd99a775f2f50443bee38b63e9 (patch) | |
| tree | 778697e612a5b4dbbf040371171403a5c700a434 /arch/mips/mm/mmap.c | |
| parent | d9ae4f18c0d2a4781c1338e6ca0f21a1e96cdb03 (diff) | |
MIPS: Add support for ARCH_MMAP_RND_{COMPAT_}BITS
arch_mmap_rnd() uses hard-coded limits of 16MB for the randomisation
of mmap within 32bit processes and 256MB in 64bit processes. Since v4.4
other arches support tuning this value in /proc/sys/vm/mmap_rnd_bits.
Add support for this to MIPS.
Set the minimum(default) number of bits randomisation for 32bit to 8 -
which with 4k pagesize is unchanged from the current 16MB total
randomness. The minimum(default) for 64bit is 12bits, again with 4k
pagesize this is the same as the current 256MB.
This patch is necessary for MIPS32 to pass the Android CTS tests, with
the number of random bits set to 15.
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Daniel Cashman <dcashman@android.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mips@linux-mips.org
Cc: kernel-hardening@lists.openwall.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14617/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/mm/mmap.c')
| -rw-r--r-- | arch/mips/mm/mmap.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c index d08ea3ff0f53..d6d92c02308d 100644 --- a/arch/mips/mm/mmap.c +++ b/arch/mips/mm/mmap.c @@ -146,14 +146,14 @@ unsigned long arch_mmap_rnd(void) { unsigned long rnd; - rnd = get_random_long(); - rnd <<= PAGE_SHIFT; +#ifdef CONFIG_COMPAT if (TASK_IS_32BIT_ADDR) - rnd &= 0xfffffful; + rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); else - rnd &= 0xffffffful; +#endif /* CONFIG_COMPAT */ + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); - return rnd; + return rnd << PAGE_SHIFT; } void arch_pick_mmap_layout(struct mm_struct *mm) |