[PATCH net] nexthop: use nlmsg_parse_deprecated()

[PATCH net] nexthop: use nlmsg_parse_deprecated()

[Eric Dumazet]

David missed that commit 8cb081746c03 ("netlink: make validation
more configurable for future strictness") has renamed nlmsg_parse()

syzbot reported :
BUG: KMSAN: uninit-value in nh_valid_get_del_req+0x6f1/0x8c0 net/ipv4/nexthop.c:1510
CPU: 0 PID: 11812 Comm: syz-executor444 Not tainted 5.3.0-rc3+ #17
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x191/0x1f0 lib/dump_stack.c:113
 kmsan_report+0x162/0x2d0 mm/kmsan/kmsan_report.c:109
 __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:294
 nh_valid_get_del_req+0x6f1/0x8c0 net/ipv4/nexthop.c:1510
 rtm_del_nexthop+0x1b1/0x610 net/ipv4/nexthop.c:1543
 rtnetlink_rcv_msg+0x115a/0x1580 net/core/rtnetlink.c:5223
 netlink_rcv_skb+0x431/0x620 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:5241
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0xf6c/0x1050 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x110f/0x1330 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg net/socket.c:657 [inline]
 ___sys_sendmsg+0x14ff/0x1590 net/socket.c:2311
 __sys_sendmmsg+0x53a/0xae0 net/socket.c:2413
 __do_sys_sendmmsg net/socket.c:2442 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2439
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2439
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Fixes: ab84be7e54fc ("net: Initial nexthop code")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: David Ahern <dsahern@gmail.com>
---
 net/ipv4/nexthop.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 5fe5a3981d4316ad8d9dbf54f5d9017b89e24038..2672e1a7b544253f2d1d0aaffd2bab9db5d76b9f 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -1304,8 +1304,8 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 	struct nlattr *tb[NHA_MAX + 1];
 	int err;
 
-	err = nlmsg_parse(nlh, sizeof(*nhm), tb, NHA_MAX, rtm_nh_policy,
-			  extack);
+	err = nlmsg_parse_deprecated(nlh, sizeof(*nhm), tb, NHA_MAX,
+				     rtm_nh_policy, extack);
 	if (err < 0)
 		return err;
 
@@ -1488,8 +1488,8 @@ static int nh_valid_get_del_req(struct nlmsghdr *nlh, u32 *id,
 	struct nlattr *tb[NHA_MAX + 1];
 	int err, i;
 
-	err = nlmsg_parse(nlh, sizeof(*nhm), tb, NHA_MAX, rtm_nh_policy,
-			  extack);
+	err = nlmsg_parse_deprecated(nlh, sizeof(*nhm), tb, NHA_MAX,
+				     rtm_nh_policy, extack);
 	if (err < 0)
 		return err;
 
@@ -1639,8 +1639,8 @@ static int nh_valid_dump_req(const struct nlmsghdr *nlh, int *dev_idx,
 	int err, i;
 	u32 idx;
 
-	err = nlmsg_parse(nlh, sizeof(*nhm), tb, NHA_MAX, rtm_nh_policy,
-			  NULL);
+	err = nlmsg_parse_deprecated(nlh, sizeof(*nhm), tb, NHA_MAX,
+				     rtm_nh_policy, NULL);
 	if (err < 0)
 		return err;
 
-- 
2.23.0.rc1.153.gdeed80330f-goog

Re: [PATCH net] nexthop: use nlmsg_parse_deprecated()

[David Ahern]

On 8/12/19 5:36 AM, Eric Dumazet wrote:
> David missed that commit 8cb081746c03 ("netlink: make validation
> more configurable for future strictness") has renamed nlmsg_parse()

Thanks for the report, Eric. It is quite likely I overlooked something
with that rename given the timing. However, the nexthop code being a new
feature is expected to use all of the strict parsing and checking. I can
take a look at this later today.

Re: [PATCH net] nexthop: use nlmsg_parse_deprecated()

[David Ahern]

On 8/12/19 5:36 AM, Eric Dumazet wrote:
> David missed that commit 8cb081746c03 ("netlink: make validation
> more configurable for future strictness") has renamed nlmsg_parse()

I think the root cause is nlmsg_parse() calling __nla_parse and not
__nlmsg_parse. Users of nlmsg_parse are missing the header validation.