[PATCH net] netlink: validate length of NLA_{BE16,BE32} types

[Pablo Neira Ayuso <pablo@netfilter.org>]

syzbot reports:

=====================================================
BUG: KMSAN: uninit-value in nla_validate_range_unsigned lib/nlattr.c:222 [inline]
BUG: KMSAN: uninit-value in nla_validate_int_range lib/nlattr.c:336 [inline]
BUG: KMSAN: uninit-value in validate_nla lib/nlattr.c:575 [inline]
BUG: KMSAN: uninit-value in __nla_validate_parse+0x2e20/0x45c0 lib/nlattr.c:631
 nla_validate_range_unsigned lib/nlattr.c:222 [inline]
 nla_validate_int_range lib/nlattr.c:336 [inline]
 validate_nla lib/nlattr.c:575 [inline]
 __nla_validate_parse+0x2e20/0x45c0 lib/nlattr.c:631
 __nla_parse+0x5f/0x70 lib/nlattr.c:728
 nla_parse_deprecated include/net/netlink.h:703 [inline]
 nfnetlink_rcv_msg+0x723/0xde0 net/netfilter/nfnetlink.c:275
 netlink_rcv_skb+0x371/0x650 net/netlink/af_netlink.c:2543
 nfnetlink_rcv+0x372/0x4950 net/netfilter/nfnetlink.c:659
 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
 netlink_unicast+0xf49/0x1250 net/netlink/af_netlink.c:1367
 netlink_sendmsg+0x1238/0x13d0 net/netlink/af_netlink.c:1908
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmsg net/socket.c:2667 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:3819 [inline]
 slab_alloc_node mm/slub.c:3860 [inline]
 kmem_cache_alloc_node+0x5cb/0xbc0 mm/slub.c:3903
 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560
 __alloc_skb+0x352/0x790 net/core/skbuff.c:651
 alloc_skb include/linux/skbuff.h:1296 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1213 [inline]
 netlink_sendmsg+0xb34/0x13d0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmsg net/socket.c:2667 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

NLA_BE16 and NLA_BE32 minimum attribute length is not validated, update
nla_attr_len and nla_attr_minlen accordingly.

After this update, kernel displays:

  netlink: 'x': attribute type 2 has an invalid length.

in case that the attribute payload is too small and it reports -ERANGE
to userspace.

Fixes: ecaf75ffd5f5 ("netlink: introduce bigendian integer types")
Reported-by: syzbot+3f497b07aa3baf2fb4d0@syzkaller.appspotmail.com
Reported-by: xingwei lee <xrivendell7@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 lib/nlattr.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/nlattr.c b/lib/nlattr.c
index ed2ab43e1b22..be9c576b6e2d 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -30,6 +30,8 @@ static const u8 nla_attr_len[NLA_TYPE_MAX+1] = {
 	[NLA_S16]	= sizeof(s16),
 	[NLA_S32]	= sizeof(s32),
 	[NLA_S64]	= sizeof(s64),
+	[NLA_BE16]	= sizeof(__be16),
+	[NLA_BE32]	= sizeof(__be32),
 };
 
 static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
@@ -43,6 +45,8 @@ static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
 	[NLA_S16]	= sizeof(s16),
 	[NLA_S32]	= sizeof(s32),
 	[NLA_S64]	= sizeof(s64),
+	[NLA_BE16]	= sizeof(__be16),
+	[NLA_BE32]	= sizeof(__be32),
 };
 
 /*
-- 
2.30.2