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 <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
wafgo · Apr 2, 2019 · 4712d37 · 4712d37
1 parent de36e16
commit 4712d37
Showing 1 changed file with 6 additions and 0 deletions.
diff --git 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);