linux-kernel - [PATCH] tty_io: Fix a missing-check bug in drivers/tty/tty

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190522014006.GB4093@zhanggen-UX430UQ>
Date:   Wed, 22 May 2019 09:40:06 +0800
From:   Gen Zhang <blackgod016574@...il.com>
To:     jslaby@...e.com
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] tty_io: Fix a missing-check bug in drivers/tty/tty_io.c

In alloc_tty_struct(), tty->dev is assigned by tty_get_device(). And it
calls class_find_device(). And class_find_device() may return NULL.
And tty->dev is dereferenced in the following codes. When 
tty_get_device() returns NULL, dereferencing this tty->dev null pointer
may cause the kernel go wrong. Thus we should check tty->dev.
Further, if tty_get_device() returns NULL, we should free tty and 
return NULL.

Signed-off-by: Gen Zhang <blackgod016574@...il.com>

---
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 033ac7e..1444b59 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3008,6 +3008,10 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
 	tty->index = idx;
 	tty_line_name(driver, idx, tty->name);
 	tty->dev = tty_get_device(tty);
+	if (!tty->dev) {
+		kfree(tty);
+		return NULL;
+	}

 	return tty;
 }