From 9046625511ad8dfbc8c6c2de16b3532c43d68d48 Mon Sep 17 00:00:00 2001
From: Jeffrey Mitchell <jeffrey.mitchell@starlab.io>
Date: Fri, 26 Feb 2021 15:00:23 -0600
Subject: [Backport 9046625511ad] ecryptfs: fix kernel panic with null dev_name

When mounting eCryptfs, a null "dev_name" argument to ecryptfs_mount()
causes a kernel panic if the parsed options are valid. The easiest way to
reproduce this is to call mount() from userspace with an existing
eCryptfs mount's options and a "source" argument of 0.

Error out if "dev_name" is null in ecryptfs_mount()

Fixes: 237fead61998 ("[PATCH] ecryptfs: fs/Makefile and fs/Kconfig")
Cc: stable@vger.kernel.org
Signed-off-by: Jeffrey Mitchell <jeffrey.mitchell@starlab.io>
Signed-off-by: Tyler Hicks <code@tyhicks.com>
---
 src/main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/main.c b/src/main.c
index 77b96737b1ffbdeea6d22294530e85ce05464dde..d66bbd2df191e5cf69310243a711dd341e3822c7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -492,6 +492,12 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
 		goto out;
 	}
 
+	if (!dev_name) {
+		rc = -EINVAL;
+		err = "Device name cannot be null";
+		goto out;
+	}
+
 	rc = ecryptfs_parse_options(sbi, raw_data, &check_ruid);
 	if (rc) {
 		err = "Error parsing options";
-- 
2.31.1