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

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 <[email protected]> know about it.

From: Jeff Mahoney <[email protected]>
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 <[email protected]>

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

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

@@ -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 [email protected] 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