From: Chengguang Xu <cgxu519@gmx.com>
Date: Fri, 15 Feb 2019 12:27:11 +0000 (+0800)
Subject: chardev: add additional check for minor range overlap
X-Git-Tag: v4.4.181~84
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cb7872f128359b7ef982780703411eb2a68a2390;p=thirdparty%2Fkernel%2Fstable.git

chardev: add additional check for minor range overlap

[ Upstream commit de36e16d1557a0b6eb328bc3516359a12ba5c25c ]

Current overlap checking cannot correctly handle
a case which is baseminor < existing baseminor &&
baseminor + minorct > existing baseminor + minorct.

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/char_dev.c b/fs/char_dev.c
index 24b142569ca9b..d0655ca894816 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -130,6 +130,12 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 			ret = -EBUSY;
 			goto out;
 		}
+
+		if (new_min < old_min && new_max > old_max) {
+			ret = -EBUSY;
+			goto out;
+		}
+
 	}
 
 	cd->next = *cp;