linux-kernel - [PATCH] staging:wlan-ng: use memdup_user instead of kmalloc/copy_from

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Date:   Sat, 13 Feb 2021 15:05:28 +0300
From:   Ivan Safonov <insafonov@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Allen Pais <apais@...ux.microsoft.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...e.com>,
        Waiman Long <longman@...hat.com>,
        Abheek Dhawan <adawesomeguy222@...il.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Ivan Safonov <insafonov@...il.com>
Subject: [PATCH] staging:wlan-ng: use memdup_user instead of kmalloc/copy_from_user

memdup_user() is shorter and safer equivalent
of kmalloc/copy_from_user pair.

Signed-off-by: Ivan Safonov <insafonov@...il.com>
---
 drivers/staging/wlan-ng/p80211netdev.c | 28 ++++++++++++--------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/staging/wlan-ng/p80211netdev.c b/drivers/staging/wlan-ng/p80211netdev.c
index a15abb2c8f54..6f9666dc0277 100644
--- a/drivers/staging/wlan-ng/p80211netdev.c
+++ b/drivers/staging/wlan-ng/p80211netdev.c
@@ -569,24 +569,22 @@ static int p80211knetdev_do_ioctl(struct net_device *dev,
 		goto bail;
 	}
 
-	/* Allocate a buf of size req->len */
-	msgbuf = kmalloc(req->len, GFP_KERNEL);
-	if (msgbuf) {
-		if (copy_from_user(msgbuf, (void __user *)req->data, req->len))
-			result = -EFAULT;
-		else
-			result = p80211req_dorequest(wlandev, msgbuf);
+	msgbuf = memdup_user(req->data, req->len);
+	if (IS_ERR(msgbuf)) {
+		result = PTR_ERR(msgbuf);
+		goto bail;
+	}
 
-		if (result == 0) {
-			if (copy_to_user
-			    ((void __user *)req->data, msgbuf, req->len)) {
-				result = -EFAULT;
-			}
+	result = p80211req_dorequest(wlandev, msgbuf);
+
+	if (result == 0) {
+		if (copy_to_user
+		    ((void __user *)req->data, msgbuf, req->len)) {
+			result = -EFAULT;
 		}
-		kfree(msgbuf);
-	} else {
-		result = -ENOMEM;
 	}
+	kfree(msgbuf);
+
 bail:
 	/* If allocate,copyfrom or copyto fails, return errno */
 	return result;
-- 
2.26.2