From: Demi Marie Obenour <demi@invisiblethingslab.com>
Date: Sat, 3 Jun 2023 14:52:44 +0000 (-0400)
Subject: dm ioctl: Refuse to create device named "." or ".."
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=81ca2dbefaabe1a2ca1c7cfc84dfd45c072c82a6;p=linux.git

dm ioctl: Refuse to create device named "." or ".."

Using either of these is going to greatly confuse userspace, as they are
not valid symlink names and so creating the usual /dev/mapper/NAME
symlink will not be possible.  As creating a device with either of these
names is almost certainly a userspace bug, just error out.

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
---

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index e172a91e88dc7..16244a7b193c0 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -771,8 +771,10 @@ static int check_name(const char *name)
 		return -EINVAL;
 	}
 
-	if (strcmp(name, DM_CONTROL_NODE) == 0) {
-		DMERR("device name cannot be \"%s\"", DM_CONTROL_NODE);
+	if (strcmp(name, DM_CONTROL_NODE) == 0 ||
+	    strcmp(name, ".") == 0 ||
+	    strcmp(name, "..") == 0) {
+		DMERR("device name cannot be \"%s\", \".\", or \"..\"", DM_CONTROL_NODE);
 		return -EINVAL;
 	}