This is a note to let you know that I've just added the patch titled
mm: fix new crash in unmapped_area_topdown()
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-fix-new-crash-in-unmapped_area_topdown.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f4cb767d76cf7ee72f97dd76f6cfa6c76a5edc89 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@xxxxxxxxxx>
Date: Tue, 20 Jun 2017 02:10:44 -0700
Subject: mm: fix new crash in unmapped_area_topdown()
From: Hugh Dickins <hughd@xxxxxxxxxx>
commit f4cb767d76cf7ee72f97dd76f6cfa6c76a5edc89 upstream.
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().
Fixes: 1be7107fbe18 ("mm: larger stack guard gap, between vmas")
Reported-by: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Debugged-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1770,7 +1770,8 @@ check_current:
/* 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 */
@@ -1873,7 +1874,8 @@ check_current:
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 */
Patches currently in stable-queue which might be from hughd@xxxxxxxxxx are
queue-3.18/mm-fix-new-crash-in-unmapped_area_topdown.patch
queue-3.18/allow-stack-to-grow-up-to-address-space-limit.patch
queue-3.18/mm-larger-stack-guard-gap-between-vmas.patch