From: Chengguang Xu <cgxu519@gmx.com>
Date: Fri, 15 Feb 2019 12:27:12 +0000 (+0800)
Subject: chardev: add a check for given minor range
X-Git-Tag: Ubuntu-5.4-5.4.0-11.14~2984^2~135
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=4712d3796f19b32241b41e538107fb7ae7a3fcff;p=mirror_ubuntu-focal-kernel.git

chardev: add a check for given minor range

register_chrdev_region() carefully checks minor range
before calling __register_chrdev_region() but there is
another path from alloc_chrdev_region() which does not
check the range properly. So add a check for given minor
range in __register_chrdev_region().

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

diff --git a/fs/char_dev.c b/fs/char_dev.c
index 8a63cfa29005..6803e98414f1 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -104,6 +104,12 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 	int ret = 0;
 	int i;
 
+	if (minorct > MINORMASK + 1 - baseminor) {
+		pr_err("CHRDEV \"%s\" minor range requested (%u-%u) is out of range of maximum range (%u-%u) for a single major\n",
+			name, baseminor, baseminor + minorct - 1, 0, MINORMASK);
+		return ERR_PTR(-EINVAL);
+	}
+
 	cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
 	if (cd == NULL)
 		return ERR_PTR(-ENOMEM);