[PATCH 4.9 011/240] ecryptfs: fix kernel panic with null dev_name

Greg Kroah-Hartman
2021-05-20T11:02:11Z

From: Jeffrey Mitchell <jeffrey.mitchell@starlab.io>

commit 9046625511ad8dfbc8c6c2de16b3532c43d68d48 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ecryptfs/main.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -506,6 +506,12 @@ static struct dentry *ecryptfs_mount(str
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";