From: Xiongwei Song <sxwjean@xxxxxxxxx>
In x86, a 64bit task may invoke a 32 bit syscall, which is in compat
syscall. Then we have to provide 32bit mapping base.
Signed-off-by: Xiongwei Song <sxwjean@xxxxxxxxx>
---
mm/util.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/mm/util.c b/mm/util.c
index 40b1a8837c0b..38326ef21a3b 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -385,14 +385,15 @@ static int mmap_is_legacy(struct rlimit *rlim_stack)
#define MIN_GAP (SZ_128M)
#define MAX_GAP (STACK_TOP / 6 * 5)
-static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
+static unsigned long mmap_base(unsigned long rnd, unsigned long task_size,
+ struct rlimit *rlim_stack)
{
unsigned long gap = rlim_stack->rlim_cur;
unsigned long pad = stack_guard_gap;
/* Account for stack randomization if necessary */
if (current->flags & PF_RANDOMIZE)
- pad += (STACK_RND_MASK << PAGE_SHIFT);
+ pad += (in_compat_syscall() ? 0x7ff : STACK_RND_MASK) << PAGE_SHIFT;
/* Values close to RLIM_INFINITY can overflow. */
if (gap + pad > gap)
@@ -403,7 +404,7 @@ static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
else if (gap > MAX_GAP)
gap = MAX_GAP;
- return PAGE_ALIGN(STACK_TOP - gap - rnd);
+ return PAGE_ALIGN(task_size - gap - rnd);
}
void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
@@ -418,7 +419,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
mm->mmap_base = mm->mmap_legacy_base;
mm->get_unmapped_area = arch_get_unmapped_area;
} else {
- mm->mmap_base = mmap_base(random_factor, rlim_stack);
+ mm->mmap_base = mmap_base(random_factor, STACK_TOP, rlim_stack);
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
}
}
--
2.30.2
