UPSTREAM: ecryptfs: don't allow mmap when the lower fs doesn't support it (7997255b) · Commits · e / devices / android_kernel_sony_msm8998

(cherry picked from commit f0fe970df3838c202ef6c07a4c2b36838ef0a88b) 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> Cc: stable@vger.kernel.org [tyhicks: clean up f_op check by using ecryptfs_file_to_lower()] Signed-off-by:

Tyler Hicks <tyhicks@canonical.com> Change-Id: I66e3670771630a25b0608f10019d1584e9ce73a6 Signed-off-by:

Amit Pundir <amit.pundir@linaro.org>

fs/ecryptfs/file.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -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_main_fops = {
		#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,