3.19.8-ckt21 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
commit 8e89a356feb6f196824a72101861d931a97ac2d2 upstream.
In preparation for splitting out ET_DYN ASLR, this refactors the use of
mmap_rnd() to be used similarly to arm and x86, and extracts the
checking of PF_RANDOMIZE.
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
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/s390/mm/mmap.c | 34 +++++++++++++++++++++++-----------
1 file changed, 23 insertions(+), 11 deletions(-)
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 179a2c2..db57078 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -62,20 +62,18 @@ static inline int mmap_is_legacy(void)
static unsigned long mmap_rnd(void)
{
- if (!(current->flags & PF_RANDOMIZE))
- return 0;
if (is_32bit_task())
return (get_random_int() & 0x7ff) << PAGE_SHIFT;
else
return (get_random_int() & mmap_rnd_mask) << PAGE_SHIFT;
}
-static unsigned long mmap_base_legacy(void)
+static unsigned long mmap_base_legacy(unsigned long rnd)
{
- return TASK_UNMAPPED_BASE + mmap_rnd();
+ return TASK_UNMAPPED_BASE + rnd;
}
-static inline unsigned long mmap_base(void)
+static inline unsigned long mmap_base(unsigned long rnd)
{
unsigned long gap = rlimit(RLIMIT_STACK);
@@ -84,7 +82,7 @@ static inline unsigned long mmap_base(void)
else if (gap > MAX_GAP)
gap = MAX_GAP;
gap &= PAGE_MASK;
- return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
+ return STACK_TOP - stack_maxrandom_size() - rnd - gap;
}
unsigned long
@@ -187,7 +185,11 @@ unsigned long randomize_et_dyn(void)
if (!is_32bit_task())
/* Align to 4GB */
base &= ~((1UL << 32) - 1);
- return base + mmap_rnd();
+
+ if (current->flags & PF_RANDOMIZE)
+ base += mmap_rnd();
+
+ return base;
}
#ifndef CONFIG_64BIT
@@ -198,15 +200,20 @@ unsigned long randomize_et_dyn(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 = mmap_base_legacy();
+ mm->mmap_base = mmap_base_legacy(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;
}
}
@@ -273,15 +280,20 @@ s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
*/
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 = mmap_base_legacy();
+ mm->mmap_base = mmap_base_legacy(random_factor);
mm->get_unmapped_area = s390_get_unmapped_area;
} else {
- mm->mmap_base = mmap_base();
+ mm->mmap_base = mmap_base(random_factor);
mm->get_unmapped_area = s390_get_unmapped_area_topdown;
}
}
--
2.7.4
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