3.19.8-ckt21 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
commit dd04cff1dceab18226853b555cf07914648a235f upstream.
In preparation for splitting out ET_DYN ASLR, this refactors the use of
mmap_rnd() to be used similarly to arm and x86. This additionally
enables mmap ASLR on legacy mmap layouts, which appeared to be missing
on arm64, and was already supported on arm. Additionally removes a
copy/pasted declaration of an unused function.
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
arch/arm64/include/asm/elf.h | 1 -
arch/arm64/mm/mmap.c | 18 +++++++++++-------
2 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 1f65be3..f724db0 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -125,7 +125,6 @@ typedef struct user_fpsimd_state elf_fpregset_t;
* the loader. We need to make sure that it is out of the way of the program
* that it will "exec", and that there is sufficient room for the brk.
*/
-extern unsigned long randomize_et_dyn(unsigned long base);
#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3)
/*
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
index 54922d1..ba776c0 100644
--- a/arch/arm64/mm/mmap.c
+++ b/arch/arm64/mm/mmap.c
@@ -49,15 +49,14 @@ static int mmap_is_legacy(void)
static unsigned long mmap_rnd(void)
{
- unsigned long rnd = 0;
+ unsigned long rnd;
- if (current->flags & PF_RANDOMIZE)
- rnd = (long)get_random_int() & STACK_RND_MASK;
+ rnd = (unsigned long)get_random_int() & STACK_RND_MASK;
return rnd << PAGE_SHIFT;
}
-static unsigned long mmap_base(void)
+static unsigned long mmap_base(unsigned long rnd)
{
unsigned long gap = rlimit(RLIMIT_STACK);
@@ -66,7 +65,7 @@ static unsigned long mmap_base(void)
else if (gap > MAX_GAP)
gap = MAX_GAP;
- return PAGE_ALIGN(STACK_TOP - gap - mmap_rnd());
+ return PAGE_ALIGN(STACK_TOP - gap - rnd);
}
/*
@@ -75,15 +74,20 @@ static 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:
*/
if (mmap_is_legacy()) {
- mm->mmap_base = TASK_UNMAPPED_BASE;
+ mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
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;
}
}
--
2.7.4
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