Patch "mm: fix overflow check in expand_upwards()" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    mm: fix overflow check in expand_upwards()

to the 4.4-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-overflow-check-in-expand_upwards.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 37511fb5c91db93d8bd6e3f52f86e5a7ff7cfcdf Mon Sep 17 00:00:00 2001
From: Helge Deller <deller@gmx.de>
Date: Fri, 14 Jul 2017 14:49:38 -0700
Subject: mm: fix overflow check in expand_upwards()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Helge Deller <deller@gmx.de>

commit 37511fb5c91db93d8bd6e3f52f86e5a7ff7cfcdf upstream.

Jörn Engel noticed that the expand_upwards() function might not return
-ENOMEM in case the requested address is (unsigned long)-PAGE_SIZE and
if the architecture didn't defined TASK_SIZE as multiple of PAGE_SIZE.

Affected architectures are arm, frv, m68k, blackfin, h8300 and xtensa
which all define TASK_SIZE as 0xffffffff, but since none of those have
an upwards-growing stack we currently have no actual issue.

Nevertheless let's fix this just in case any of the architectures with
an upward-growing stack (currently parisc, metag and partly ia64) define
TASK_SIZE similar.

Link: http://lkml.kernel.org/r/20170702192452.GA11868@p100.box
Fixes: bd726c90b6b8 ("Allow stack to grow up to address space limit")
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: Jörn Engel <joern@purestorage.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 mm/mmap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2176,7 +2176,7 @@ int expand_upwards(struct vm_area_struct
 
 	/* Guard against exceeding limits of the address space. */
 	address &= PAGE_MASK;
-	if (address >= TASK_SIZE)
+	if (address >= (TASK_SIZE & PAGE_MASK))
 		return -ENOMEM;
 	address += PAGE_SIZE;
 


Patches currently in stable-queue which might be from deller@gmx.de are

queue-4.4/parisc-use-compat_sys_keyctl.patch
queue-4.4/mm-fix-overflow-check-in-expand_upwards.patch
queue-4.4/parisc-dma-api-return-error-instead-of-bug_on-for-dma-ops-on-non-dma-devs.patch
queue-4.4/parisc-mm-ensure-irqs-are-off-in-switch_mm.patch
queue-4.4/parisc-report-sigsegv-instead-of-sigbus-when-running-out-of-stack.patch