Patch "device-dax: fail all private mapping attempts" has been added to the 4.8-stable tree

Patch "device-dax: fail all private mapping attempts" has been added to the 4.8-stable tree

[gregkh]

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

    device-dax: fail all private mapping attempts

to the 4.8-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:
     device-dax-fail-all-private-mapping-attempts.patch
and it can be found in the queue-4.8 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 4cb19355ea19995941ccaad115dbfac6b75215ca Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@intel.com>
Date: Wed, 16 Nov 2016 09:00:38 -0800
Subject: device-dax: fail all private mapping attempts

From: Dan Williams <dan.j.williams@intel.com>

commit 4cb19355ea19995941ccaad115dbfac6b75215ca upstream.

The device-dax implementation originally tried to be tricky and allow
private read-only mappings, but in the process allowed writable
MAP_PRIVATE + MAP_NORESERVE mappings.  For simplicity and predictability
just fail all private mapping attempts since device-dax memory is
statically allocated and will never support overcommit.

Cc: Dave Hansen <dave.hansen@linux.intel.com>
Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
Reported-by: Pawel Lebioda <pawel.lebioda@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/dax/dax.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -323,8 +323,8 @@ static int check_vma(struct dax_dev *dax
 	if (!dax_dev->alive)
 		return -ENXIO;
 
-	/* prevent private / writable mappings from being established */
-	if ((vma->vm_flags & (VM_NORESERVE|VM_SHARED|VM_WRITE)) == VM_WRITE) {
+	/* prevent private mappings from being established */
+	if ((vma->vm_flags & VM_SHARED) != VM_SHARED) {
 		dev_info(dev, "%s: %s: fail, attempted private mapping\n",
 				current->comm, func);
 		return -EINVAL;


Patches currently in stable-queue which might be from dan.j.williams@intel.com are

queue-4.8/device-dax-fail-all-private-mapping-attempts.patch
queue-4.8/device-dax-check-devm_nsio_enable-return-value.patch