From: Andy Whitcroft <apw@shadowen.org>
Date: Sun, 6 May 2007 21:49:33 +0000 (-0700)
Subject: tty_register_driver: only allocate tty instances when defined
X-Git-Tag: v2.6.22-rc1~969
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=543691a6cd70b606dd9bed5e77b120c5d9c5c506;p=linux-2.6

tty_register_driver: only allocate tty instances when defined

If device->num is zero we attempt to kmalloc() zero bytes.  When SLUB is
enabled this returns a null pointer and take that as an allocation failure
and fail the device register.  Check for no devices and avoid the
allocation.

[akpm: opportunistic kzalloc() conversion]
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 7a32df5949..389da364e6 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -3720,11 +3720,10 @@ int tty_register_driver(struct tty_driver *driver)
 	if (driver->flags & TTY_DRIVER_INSTALLED)
 		return 0;
 
-	if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
-		p = kmalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
+	if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
+		p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
 		if (!p)
 			return -ENOMEM;
-		memset(p, 0, driver->num * 3 * sizeof(void *));
 	}
 
 	if (!driver->major) {