linux-kernel - [PATCH] agp: use memdup

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Message-Id: <df8091d4c64a0d5a7ab0a5989f34552a5eebd15e.1493778999.git.geliangtang@gmail.com>
Date:   Sat,  6 May 2017 23:42:15 +0800
From:   Geliang Tang <geliangtang@...il.com>
To:     David Airlie <airlied@...ux.ie>
Cc:     Geliang Tang <geliangtang@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] agp: use memdup_user

Use memdup_user() helper instead of open-coding to simplify the code.

Signed-off-by: Geliang Tang <geliangtang@...il.com>
---
 drivers/char/agp/compat_ioctl.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/char/agp/compat_ioctl.c b/drivers/char/agp/compat_ioctl.c
index 2053f70..a0a3cf0 100644
--- a/drivers/char/agp/compat_ioctl.c
+++ b/drivers/char/agp/compat_ioctl.c
@@ -98,9 +98,10 @@ static int compat_agpioc_reserve_wrap(struct agp_file_private *priv, void __user
 		if (ureserve.seg_count >= 16384)
 			return -EINVAL;
 
-		usegment = kmalloc(sizeof(*usegment) * ureserve.seg_count, GFP_KERNEL);
-		if (!usegment)
-			return -ENOMEM;
+		usegment = memdup_user((void __user *)ureserve.seg_list,
+				       sizeof(*usegment) * ureserve.seg_count);
+		if (IS_ERR(usegment))
+			return PTR_ERR(usegment);
 
 		ksegment = kmalloc(sizeof(*ksegment) * kreserve.seg_count, GFP_KERNEL);
 		if (!ksegment) {
@@ -108,13 +109,6 @@ static int compat_agpioc_reserve_wrap(struct agp_file_private *priv, void __user
 			return -ENOMEM;
 		}
 
-		if (copy_from_user(usegment, (void __user *) ureserve.seg_list,
-				   sizeof(*usegment) * ureserve.seg_count)) {
-			kfree(usegment);
-			kfree(ksegment);
-			return -EFAULT;
-		}
-
 		for (seg = 0; seg < ureserve.seg_count; seg++) {
 			ksegment[seg].pg_start = usegment[seg].pg_start;
 			ksegment[seg].pg_count = usegment[seg].pg_count;
-- 
2.9.3