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| author |   Kees Cook <keescook@chromium.org> | 2015-04-14 15:47:54 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-14 16:49:05 -0700 |
| commit | ed6322746afb74c2509e2f3a6464182793b16eb9 (patch) | |
| tree | 0e1998c27632be0877cb01ea547f41611a7834b9 | |
| parent | mips: extract logic for mmap_rnd() (diff) | |
| download | linux-dev-ed6322746afb74c2509e2f3a6464182793b16eb9.tar.xz linux-dev-ed6322746afb74c2509e2f3a6464182793b16eb9.zip | |
powerpc: standardize mmap_rnd() usage
In preparation for splitting out ET_DYN ASLR, this refactors the use of
mmap_rnd() to be used similarly to arm and x86.
(Can mmap ASLR be safely enabled in the legacy mmap case here? Other
archs use "mm->mmap_base = TASK_UNMAPPED_BASE + random_factor".)
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | arch/powerpc/mm/mmap.c | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c index cb8bdbe4972f..1ad2299d795d 100644 --- a/arch/powerpc/mm/mmap.c +++ b/arch/powerpc/mm/mmap.c @@ -55,19 +55,18 @@ static inline int mmap_is_legacy(void) static unsigned long mmap_rnd(void) { - unsigned long rnd = 0; + unsigned long rnd; + + /* 8MB for 32bit, 1GB for 64bit */ + if (is_32bit_task()) + rnd = (unsigned long)get_random_int() % (1<<(23-PAGE_SHIFT)); + else + rnd = (unsigned long)get_random_int() % (1<<(30-PAGE_SHIFT)); - if (current->flags & PF_RANDOMIZE) { - /* 8MB for 32bit, 1GB for 64bit */ - if (is_32bit_task()) - rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT))); - else - rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT))); - } return rnd << PAGE_SHIFT; } -static inline unsigned long mmap_base(void) +static inline unsigned long mmap_base(unsigned long rnd) { unsigned long gap = rlimit(RLIMIT_STACK); @@ -76,7 +75,7 @@ static inline unsigned long mmap_base(void) else if (gap > MAX_GAP) gap = MAX_GAP; - return PAGE_ALIGN(TASK_SIZE - gap - mmap_rnd()); + return PAGE_ALIGN(TASK_SIZE - gap - rnd); } /* @@ -85,6 +84,11 @@ static inline unsigned long mmap_base(void) */ void arch_pick_mmap_layout(struct mm_struct *mm) { + unsigned long random_factor = 0UL; + + if (current->flags & PF_RANDOMIZE) + random_factor = mmap_rnd(); + /* * Fall back to the standard layout if the personality * bit is set, or if the expected stack growth is unlimited: @@ -93,7 +97,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm) mm->mmap_base = TASK_UNMAPPED_BASE; mm->get_unmapped_area = arch_get_unmapped_area; } else { - mm->mmap_base = mmap_base(); + mm->mmap_base = mmap_base(random_factor); mm->get_unmapped_area = arch_get_unmapped_area_topdown; } } |