linux-kernel - [PATCH v2] IB/core: Use memdup_user() rather than duplicating its implementation

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Message-ID: <3a5989cb-5a01-f502-c7fc-c489079ee73e@users.sourceforge.net>
Date:   Mon, 22 Aug 2016 18:30:33 +0200
From:   SF Markus Elfring <elfring@...rs.sourceforge.net>
To:     linux-rdma@...r.kernel.org, Doug Ledford <dledford@...hat.com>,
        Hal Rosenstock <hal.rosenstock@...il.com>,
        Joe Perches <joe@...ches.com>,
        Sean Hefty <sean.hefty@...el.com>,
        Yann Droneaud <ydroneaud@...eya.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        Julia Lawall <julia.lawall@...6.fr>
Subject: [PATCH v2] IB/core: Use memdup_user() rather than duplicating its
 implementation

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Mon, 22 Aug 2016 18:23:24 +0200

* Reuse existing functionality from memdup_user() instead of keeping
  duplicate source code.

  This issue was detected by using the Coccinelle software.

* The local variable "ret" will be set to an appropriate value a bit later.
  Thus omit the explicit initialisation at the beginning.

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---

v2: The desired changes were put into a single patch instead of
    distributing them over two update steps.

 include/rdma/ib_verbs.h | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 6f667dd..0d8100f 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2199,22 +2199,17 @@ static inline bool ib_is_udata_cleared(struct ib_udata *udata,
 				       size_t len)
 {
 	const void __user *p = udata->inbuf + offset;
-	bool ret = false;
+	bool ret;
 	u8 *buf;
 
 	if (len > USHRT_MAX)
 		return false;
 
-	buf = kmalloc(len, GFP_KERNEL);
-	if (!buf)
+	buf = memdup_user(p, len);
+	if (IS_ERR(buf))
 		return false;
 
-	if (copy_from_user(buf, p, len))
-		goto free;
-
 	ret = !memchr_inv(buf, 0, len);
-
-free:
 	kfree(buf);
 	return ret;
 }
-- 
2.9.3