From: Johannes Berg <johannes.berg@intel.com>
Date: Wed, 26 Sep 2018 11:15:31 +0200
Subject: [PATCH] netlink: make validation_data const
Patch-mainline: v4.20-rc1
Git-commit: 48fde90a78f8c67e2bec5061f9725fe363519feb
References: bsc#1152107 CVE-2019-16746

The validation data is only used within the policy that
should usually already be const, and isn't changed in any
code that uses it. Therefore, make the validation_data
pointer const.

While at it, remove the duplicate variable in the bitfield
validation that I'd otherwise have to change to const.

Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Cho, Yu-Chen <acho@suse.com>
---
 include/net/netlink.h |    2 +-
 lib/nlattr.c          |    5 ++---
 2 files changed, 3 insertions(+), 4 deletions(-)

--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -232,7 +232,7 @@ enum {
 struct nla_policy {
 	u16		type;
 	u16		len;
-	void            *validation_data;
+	const void     *validation_data;
 };
 
 /**
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -28,12 +28,11 @@ static const u8 nla_attr_minlen[NLA_TYPE
 };
 
 static int validate_nla_bitfield32(const struct nlattr *nla,
-				   u32 *valid_flags_allowed)
+				   const u32 *valid_flags_mask)
 {
 	const struct nla_bitfield32 *bf = nla_data(nla);
-	u32 *valid_flags_mask = valid_flags_allowed;
 
-	if (!valid_flags_allowed)
+	if (!valid_flags_mask)
 		return -EINVAL;
 
 	/*disallow invalid bit selector */