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: 237fead ("[PATCH] ecryptfs: fs/Makefile and fs/Kconfig")
Cc: [email protected]
Signed-off-by: Jeffrey Mitchell <[email protected]>
Signed-off-by: Tyler Hicks <[email protected]>

Author: JeffreyMitchellSL

fs/ecryptfs/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";