Patch "ecryptfs: don't allow mmap when the lower fs doesn't support it" has been added to the 4.4-stable tree

Patch "ecryptfs: don't allow mmap when the lower fs doesn't support it" has been added to the 4.4-stable tree

[gregkh]

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

    ecryptfs: don't allow mmap when the lower fs doesn't support it

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:
     ecryptfs-don-t-allow-mmap-when-the-lower-fs-doesn-t-support-it.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 f0fe970df3838c202ef6c07a4c2b36838ef0a88b Mon Sep 17 00:00:00 2001
From: Jeff Mahoney <jeffm@suse.com>
Date: Tue, 5 Jul 2016 17:32:30 -0400
Subject: ecryptfs: don't allow mmap when the lower fs doesn't support it

From: Jeff Mahoney <jeffm@suse.com>

commit f0fe970df3838c202ef6c07a4c2b36838ef0a88b upstream.

There are legitimate reasons to disallow mmap on certain files, notably
in sysfs or procfs.  We shouldn't emulate mmap support on file systems
that don't offer support natively.

CVE-2016-1583

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
[tyhicks: clean up f_op check by using ecryptfs_file_to_lower()]
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ecryptfs/file.c |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -170,6 +170,19 @@ out:
 	return rc;
 }
 
+static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct file *lower_file = ecryptfs_file_to_lower(file);
+	/*
+	 * Don't allow mmap on top of file systems that don't support it
+	 * natively.  If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
+	 * allows recursive mounting, this will need to be extended.
+	 */
+	if (!lower_file->f_op->mmap)
+		return -ENODEV;
+	return generic_file_mmap(file, vma);
+}
+
 /**
  * ecryptfs_open
  * @inode: inode speciying file to open
@@ -364,7 +377,7 @@ const struct file_operations ecryptfs_ma
 #ifdef CONFIG_COMPAT
 	.compat_ioctl = ecryptfs_compat_ioctl,
 #endif
-	.mmap = generic_file_mmap,
+	.mmap = ecryptfs_mmap,
 	.open = ecryptfs_open,
 	.flush = ecryptfs_flush,
 	.release = ecryptfs_release,


Patches currently in stable-queue which might be from jeffm@suse.com are

queue-4.4/ecryptfs-don-t-allow-mmap-when-the-lower-fs-doesn-t-support-it.patch
queue-4.4/revert-ecryptfs-forbid-opening-files-without-mmap-handler.patch