ipv6: make sure to initialize sockc.tsflags before first use

In the case udp_sk(sk)->pending is AF_INET6, udpv6_sendmsg() would
jump to do_append_data, skipping the initialization of sockc.tsflags.
Fix the problem by moving sockc.tsflags initialization earlier.

The bug was detected with KMSAN.

Fixes: c14ac9451c34 ("sock: enable timestamping using control messages")
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 4e4c401e3bc69020deaa4af1c10633288faedf13..e28082f0a307eb68ac13987580d8d9f65358212f 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1035,6 +1035,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
        ipc6.hlimit = -1;
        ipc6.tclass = -1;
        ipc6.dontfrag = -1;
+       sockc.tsflags = sk->sk_tsflags;
 
        /* destination address check */
        if (sin6) {
@@ -1159,7 +1160,6 @@ do_udp_sendmsg:
 
        fl6.flowi6_mark = sk->sk_mark;
        fl6.flowi6_uid = sk->sk_uid;
-       sockc.tsflags = sk->sk_tsflags;
 
        if (msg->msg_controllen) {
                opt = &opt_space;