netdev - [PATCHv3 net] net: use struct_group to copy ip/ipv6 header addresses

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Message-Id: <20221115142400.1204786-1-liuhangbin@gmail.com>
Date:   Tue, 15 Nov 2022 22:24:00 +0800
From:   Hangbin Liu <liuhangbin@...il.com>
To:     netdev@...r.kernel.org
Cc:     Jay Vosburgh <j.vosburgh@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jonathan Toppins <jtoppins@...hat.com>,
        Paolo Abeni <pabeni@...hat.com>,
        David Ahern <dsahern@...il.com>,
        Tom Herbert <tom@...bertland.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Hangbin Liu <liuhangbin@...il.com>,
        kernel test robot <lkp@...el.com>
Subject: [PATCHv3 net] net: use struct_group to copy ip/ipv6 header addresses

kernel test robot reported warnings when build bonding module with
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/net/bonding/:

                 from ../drivers/net/bonding/bond_main.c:35:
In function ‘fortify_memcpy_chk’,
    inlined from ‘iph_to_flow_copy_v4addrs’ at ../include/net/ip.h:566:2,
    inlined from ‘bond_flow_ip’ at ../drivers/net/bonding/bond_main.c:3984:3:
../include/linux/fortify-string.h:413:25: warning: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of f
ield (2nd parameter); maybe use struct_group()? [-Wattribute-warning]
  413 |                         __read_overflow2_field(q_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘fortify_memcpy_chk’,
    inlined from ‘iph_to_flow_copy_v6addrs’ at ../include/net/ipv6.h:900:2,
    inlined from ‘bond_flow_ip’ at ../drivers/net/bonding/bond_main.c:3994:3:
../include/linux/fortify-string.h:413:25: warning: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of f
ield (2nd parameter); maybe use struct_group()? [-Wattribute-warning]
  413 |                         __read_overflow2_field(q_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is because we try to copy the whole ip/ip6 address to the flow_key,
while we only point the to ip/ip6 saddr. Note that since these are UAPI
headers, __struct_group() is used to avoid the compiler warnings.

Reported-by: kernel test robot <lkp@...el.com>
Fixes: c3f8324188fa ("net: Add full IPv6 addresses to flow_keys")
Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
---
v3: use __struct_group as struct iphdr/ipv6hdr is defined in uapi
v2: use struct_group() instaed of memcpy twice.
---
 include/net/ip.h          | 2 +-
 include/net/ipv6.h        | 2 +-
 include/uapi/linux/ip.h   | 6 ++++--
 include/uapi/linux/ipv6.h | 6 ++++--
 4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/include/net/ip.h b/include/net/ip.h
index 038097c2a152..144bdfbb25af 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -563,7 +563,7 @@ static inline void iph_to_flow_copy_v4addrs(struct flow_keys *flow,
 	BUILD_BUG_ON(offsetof(typeof(flow->addrs), v4addrs.dst) !=
 		     offsetof(typeof(flow->addrs), v4addrs.src) +
 			      sizeof(flow->addrs.v4addrs.src));
-	memcpy(&flow->addrs.v4addrs, &iph->saddr, sizeof(flow->addrs.v4addrs));
+	memcpy(&flow->addrs.v4addrs, &iph->addrs, sizeof(flow->addrs.v4addrs));
 	flow->control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
 }
 
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 37943ba3a73c..d383c895592a 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -897,7 +897,7 @@ static inline void iph_to_flow_copy_v6addrs(struct flow_keys *flow,
 	BUILD_BUG_ON(offsetof(typeof(flow->addrs), v6addrs.dst) !=
 		     offsetof(typeof(flow->addrs), v6addrs.src) +
 		     sizeof(flow->addrs.v6addrs.src));
-	memcpy(&flow->addrs.v6addrs, &iph->saddr, sizeof(flow->addrs.v6addrs));
+	memcpy(&flow->addrs.v6addrs, &iph->addrs, sizeof(flow->addrs.v6addrs));
 	flow->control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
 }
 
diff --git a/include/uapi/linux/ip.h b/include/uapi/linux/ip.h
index 961ec16a26b8..874a92349bf5 100644
--- a/include/uapi/linux/ip.h
+++ b/include/uapi/linux/ip.h
@@ -100,8 +100,10 @@ struct iphdr {
 	__u8	ttl;
 	__u8	protocol;
 	__sum16	check;
-	__be32	saddr;
-	__be32	daddr;
+	__struct_group(/* no tag */, addrs, /* no attrs */,
+		__be32	saddr;
+		__be32	daddr;
+	);
 	/*The options start here. */
 };
 
diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
index 03cdbe798fe3..81f4243bebb1 100644
--- a/include/uapi/linux/ipv6.h
+++ b/include/uapi/linux/ipv6.h
@@ -130,8 +130,10 @@ struct ipv6hdr {
 	__u8			nexthdr;
 	__u8			hop_limit;
 
-	struct	in6_addr	saddr;
-	struct	in6_addr	daddr;
+	__struct_group(/* no tag */, addrs, /* no attrs */,
+		struct	in6_addr	saddr;
+		struct	in6_addr	daddr;
+	);
 };
 
 
-- 
2.38.1