From: Stephan Mueller <smueller@chronox.de>
Date: Mon, 16 May 2016 00:53:36 +0000 (+0200)
Subject: crypto: user - no parsing of CRYPTO_MSG_GETALG
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=eed1e1afd8d542d9644534c1b712599b5d680007;p=linux-beck.git

crypto: user - no parsing of CRYPTO_MSG_GETALG

The CRYPTO_MSG_GETALG netlink message type provides a buffer to the
kernel to retrieve information from the kernel. The data buffer will not
provide any input and will not be read. Hence the nlmsg_parse is not
applicable to this netlink message type.

This patch fixes the following kernel log message when using this
netlink interface:

netlink: 208 bytes leftover after parsing attributes in process `XXX'.

Patch successfully tested with libkcapi from [1] which uses
CRYPTO_MSG_GETALG to obtain cipher-specific information from the kernel.

[1] http://www.chronox.de/libkcapi.html

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

diff --git a/crypto/crypto_user.c b/crypto/crypto_user.c
index 43fe85f20d57..f71960dea882 100644
--- a/crypto/crypto_user.c
+++ b/crypto/crypto_user.c
@@ -516,10 +516,12 @@ static int crypto_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 		return err;
 	}
 
-	err = nlmsg_parse(nlh, crypto_msg_min[type], attrs, CRYPTOCFGA_MAX,
-			  crypto_policy);
-	if (err < 0)
-		return err;
+	if (type != (CRYPTO_MSG_GETALG - CRYPTO_MSG_BASE)) {
+		err = nlmsg_parse(nlh, crypto_msg_min[type], attrs,
+				  CRYPTOCFGA_MAX, crypto_policy);
+		if (err < 0)
+			return err;
+	}
 
 	if (link->doit == NULL)
 		return -EINVAL;