The patch titled
Subject: arm64/mmap: properly account for stack randomization in mmap_base
has been removed from the -mm tree. Its filename was
arm64-mmap-properly-account-for-stack-randomization-in-mmap_base.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Rik van Riel <riel@xxxxxxxxxx>
Subject: arm64/mmap: properly account for stack randomization in mmap_base
When RLIMIT_STACK is, for example, 256MB, the current code results in a
gap between the top of the task and mmap_base of 256MB, failing to take
into account the amount by which the stack address was randomized. In
other words, the stack gets less than RLIMIT_STACK space.
Ensure that the gap between the stack and mmap_base always takes stack
randomization and the stack guard gap into account.
Obtained from Daniel Micay's linux-hardened tree.
Link: http://lkml.kernel.org/r/20170622200033.25714-3-riel@xxxxxxxxxx
Signed-off-by: Daniel Micay <danielmicay@xxxxxxxxx>
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Reported-by: Florian Weimer <fweimer@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Daniel Micay <danielmicay@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/mm/mmap.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff -puN arch/arm64/mm/mmap.c~arm64-mmap-properly-account-for-stack-randomization-in-mmap_base arch/arm64/mm/mmap.c
--- a/arch/arm64/mm/mmap.c~arm64-mmap-properly-account-for-stack-randomization-in-mmap_base
+++ a/arch/arm64/mm/mmap.c
@@ -35,7 +35,7 @@
* Leave enough space between the mmap area and the stack to honour ulimit in
* the face of randomisation.
*/
-#define MIN_GAP (SZ_128M + ((STACK_RND_MASK << PAGE_SHIFT) + 1))
+#define MIN_GAP (SZ_128M)
#define MAX_GAP (STACK_TOP/6*5)
static int mmap_is_legacy(void)
@@ -65,6 +65,11 @@ unsigned long arch_mmap_rnd(void)
static unsigned long mmap_base(unsigned long rnd)
{
unsigned long gap = rlimit(RLIMIT_STACK);
+ unsigned long pad = (STACK_RND_MASK << PAGE_SHIFT) + stack_guard_gap;
+
+ /* Values close to RLIM_INFINITY can overflow. */
+ if (gap + pad > gap)
+ gap += pad;
if (gap < MIN_GAP)
gap = MIN_GAP;
_
Patches currently in -mm which might be from riel@xxxxxxxxxx are
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