linux-kernel - [PATCH v2] s390/raw3270: Handle memory allocation failures in raw3270_setup

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Date: Tue, 25 Jun 2024 10:32:26 +0900
From: yskelg@...il.com
To: Harald Freudenberger <freude@...ux.ibm.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Markus Elfring <Markus.Elfring@....de>
Cc: MichelleJin <shjy180909@...il.com>,
	linux-s390@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yunseong Kim <yskelg@...il.com>
Subject: [PATCH v2] s390/raw3270: Handle memory allocation failures in raw3270_setup_console()

From: Yunseong Kim <yskelg@...il.com>

A null pointer is stored in a local variable after a call of the function
"kzalloc" failed. This pointer was passed to a subsequent call of the
function "raw3270_setup_device" where an undesirable dereference will be
performed then. Thus add corresponding return value checks.
The allocated each memory areas are immediately overwritten by the called
function zero-initialisation be omitted by calling the "kmalloc" instead.
After "ccw_device_enable_console" succeeds, set the bit raw3270 flag to
RAW3270_FLAGS_CONSOLE.

Fixes: 33403dcfcdfd ("[S390] 3270 console: convert from bootmem to slab")
Cc: linux-s390@...r.kernel.org
Signed-off-by: Yunseong Kim <yskelg@...il.com>
---
 drivers/s390/char/raw3270.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/s390/char/raw3270.c b/drivers/s390/char/raw3270.c
index c57694be9bd3..4f3f98bcbc83 100644
--- a/drivers/s390/char/raw3270.c
+++ b/drivers/s390/char/raw3270.c
@@ -811,18 +811,28 @@ struct raw3270 __init *raw3270_setup_console(void)
 	if (IS_ERR(cdev))
 		return ERR_CAST(cdev);
 
-	rp = kzalloc(sizeof(*rp), GFP_KERNEL | GFP_DMA);
-	ascebc = kzalloc(256, GFP_KERNEL);
+	rp = kmalloc(sizeof(*rp), GFP_KERNEL | GFP_DMA);
+	if (!rp)
+		return ERR_PTR(-ENOMEM);
+	ascebc = kmalloc(256, GFP_KERNEL);
+	if (!ascebc) {
+		kfree(rp);
+		return ERR_PTR(-ENOMEM);
+	}
 	rc = raw3270_setup_device(cdev, rp, ascebc);
-	if (rc)
+	if (rc) {
+		kfree(ascebc);
+		kfree(rp);
 		return ERR_PTR(rc);
-	set_bit(RAW3270_FLAGS_CONSOLE, &rp->flags);
-
+	}
 	rc = ccw_device_enable_console(cdev);
 	if (rc) {
 		ccw_device_destroy_console(cdev);
+		kfree(ascebc);
+		kfree(rp);
 		return ERR_PTR(rc);
 	}
+	set_bit(RAW3270_FLAGS_CONSOLE, &rp->flags);
 
 	spin_lock_irqsave(get_ccwdev_lock(rp->cdev), flags);
 	do {
-- 
2.45.2