48 lines
1.9 KiB
Diff
48 lines
1.9 KiB
Diff
|
From f4cb767d76cf7ee72f97dd76f6cfa6c76a5edc89 Mon Sep 17 00:00:00 2001
|
||
|
|
From: Hugh Dickins <hughd@google.com>
|
||
|
|
Date: Tue, 20 Jun 2017 02:10:44 -0700
|
||
|
|
Subject: [PATCH] mm: fix new crash in unmapped_area_topdown()
|
||
|
|
|
||
|
|
Trinity gets kernel BUG at mm/mmap.c:1963! in about 3 minutes of
|
||
|
|
mmap testing. That's the VM_BUG_ON(gap_end < gap_start) at the
|
||
|
|
end of unmapped_area_topdown(). Linus points out how MAP_FIXED
|
||
|
|
(which does not have to respect our stack guard gap intentions)
|
||
|
|
could result in gap_end below gap_start there. Fix that, and
|
||
|
|
the similar case in its alternative, unmapped_area().
|
||
|
|
|
||
|
|
Cc: stable@vger.kernel.org
|
||
|
|
Fixes: 1be7107fbe18 ("mm: larger stack guard gap, between vmas")
|
||
|
|
Reported-by: Dave Jones <davej@codemonkey.org.uk>
|
||
|
|
Debugged-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
|
Signed-off-by: Hugh Dickins <hughd@google.com>
|
||
|
|
Acked-by: Michal Hocko <mhocko@suse.com>
|
||
|
|
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
|
---
|
||
|
|
mm/mmap.c | 6 ++++--
|
||
|
|
1 file changed, 4 insertions(+), 2 deletions(-)
|
||
|
|
|
||
|
|
diff --git a/mm/mmap.c b/mm/mmap.c
|
||
|
|
index 8e07976d5e477..290b77d9a01e0 100644
|
||
|
|
--- a/mm/mmap.c
|
||
|
|
+++ b/mm/mmap.c
|
||
|
|
@@ -1817,7 +1817,8 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
|
||
|
|
/* Check if current node has a suitable gap */
|
||
|
|
if (gap_start > high_limit)
|
||
|
|
return -ENOMEM;
|
||
|
|
- if (gap_end >= low_limit && gap_end - gap_start >= length)
|
||
|
|
+ if (gap_end >= low_limit &&
|
||
|
|
+ gap_end > gap_start && gap_end - gap_start >= length)
|
||
|
|
goto found;
|
||
|
|
|
||
|
|
/* Visit right subtree if it looks promising */
|
||
|
|
@@ -1920,7 +1921,8 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
|
||
|
|
gap_end = vm_start_gap(vma);
|
||
|
|
if (gap_end < low_limit)
|
||
|
|
return -ENOMEM;
|
||
|
|
- if (gap_start <= high_limit && gap_end - gap_start >= length)
|
||
|
|
+ if (gap_start <= high_limit &&
|
||
|
|
+ gap_end > gap_start && gap_end - gap_start >= length)
|
||
|
|
goto found;
|
||
|
|
|
||
|
|
/* Visit left subtree if it looks promising */
|