udp: annotate data-races around up->pending

[ Upstream commit 482521d8e0c6520429478aa6866cd44128b33d5d ]

up->pending can be read without holding the socket lock,
as pointed out by syzbot [1]

Add READ_ONCE() in lockless contexts, and WRITE_ONCE()
on write side.

[1]
BUG: KCSAN: data-race in udpv6_sendmsg / udpv6_sendmsg

write to 0xffff88814e5eadf0 of 4 bytes by task 15547 on cpu 1:
 udpv6_sendmsg+0x1405/0x1530 net/ipv6/udp.c:1596
 inet6_sendmsg+0x63/0x80 net/ipv6/af_inet6.c:657
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x257/0x310 net/socket.c:2192
 __do_sys_sendto net/socket.c:2204 [inline]
 __se_sys_sendto net/socket.c:2200 [inline]
 __x64_sys_sendto+0x78/0x90 net/socket.c:2200
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88814e5eadf0 of 4 bytes by task 15551 on cpu 0:
 udpv6_sendmsg+0x22c/0x1530 net/ipv6/udp.c:1373
 inet6_sendmsg+0x63/0x80 net/ipv6/af_inet6.c:657
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2586
 ___sys_sendmsg net/socket.c:2640 [inline]
 __sys_sendmmsg+0x269/0x500 net/socket.c:2726
 __do_sys_sendmmsg net/socket.c:2755 [inline]
 __se_sys_sendmmsg net/socket.c:2752 [inline]
 __x64_sys_sendmmsg+0x57/0x60 net/socket.c:2752
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000000 -> 0x0000000a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15551 Comm: syz-executor.1 Tainted: G        W          6.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot+8d482d0e407f665d9d10@syzkaller.appspotmail.com
Link: https://lore.kernel.org/netdev/0000000000009e46c3060ebcdffd@google.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index c3ff984..bd12a76 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -805,7 +805,7 @@ void udp_flush_pending_frames(struct sock *sk)
 
        if (up->pending) {
                up->len = 0;
-               up->pending = 0;
+               WRITE_ONCE(up->pending, 0);
                ip_flush_pending_frames(sk);
        }
 }
@@ -993,7 +993,7 @@ int udp_push_pending_frames(struct sock *sk)
 
 out:
        up->len = 0;
-       up->pending = 0;
+       WRITE_ONCE(up->pending, 0);
        return err;
 }
 EXPORT_SYMBOL(udp_push_pending_frames);
@@ -1069,7 +1069,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
        getfrag = is_udplite ? udplite_getfrag : ip_generic_getfrag;
 
        fl4 = &inet->cork.fl.u.ip4;
-       if (up->pending) {
+       if (READ_ONCE(up->pending)) {
                /*
                 * There are pending frames.
                 * The socket lock must be held while it's corked.
@@ -1265,7 +1265,7 @@ back_from_confirm:
        fl4->saddr = saddr;
        fl4->fl4_dport = dport;
        fl4->fl4_sport = inet->inet_sport;
-       up->pending = AF_INET;
+       WRITE_ONCE(up->pending, AF_INET);
 
 do_append_data:
        up->len += ulen;
@@ -1277,7 +1277,7 @@ do_append_data:
        else if (!corkreq)
                err = udp_push_pending_frames(sk);
        else if (unlikely(skb_queue_empty(&sk->sk_write_queue)))
-               up->pending = 0;
+               WRITE_ONCE(up->pending, 0);
        release_sock(sk);
 
 out:
@@ -1315,7 +1315,7 @@ void udp_splice_eof(struct socket *sock)
        struct sock *sk = sock->sk;
        struct udp_sock *up = udp_sk(sk);
 
-       if (!up->pending || udp_test_bit(CORK, sk))
+       if (!READ_ONCE(up->pending) || udp_test_bit(CORK, sk))
                return;
 
        lock_sock(sk);

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index f60ba42..f1170dc 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1134,7 +1134,7 @@ static void udp_v6_flush_pending_frames(struct sock *sk)
                udp_flush_pending_frames(sk);
        else if (up->pending) {
                up->len = 0;
-               up->pending = 0;
+               WRITE_ONCE(up->pending, 0);
                ip6_flush_pending_frames(sk);
        }
 }
@@ -1312,7 +1312,7 @@ static int udp_v6_push_pending_frames(struct sock *sk)
                              &inet_sk(sk)->cork.base);
 out:
        up->len = 0;
-       up->pending = 0;
+       WRITE_ONCE(up->pending, 0);
        return err;
 }
 
@@ -1369,7 +1369,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                default:
                        return -EINVAL;
                }
-       } else if (!up->pending) {
+       } else if (!READ_ONCE(up->pending)) {
                if (sk->sk_state != TCP_ESTABLISHED)
                        return -EDESTADDRREQ;
                daddr = &sk->sk_v6_daddr;
@@ -1400,8 +1400,8 @@ do_udp_sendmsg:
                return -EMSGSIZE;
 
        getfrag  =  is_udplite ?  udplite_getfrag : ip_generic_getfrag;
-       if (up->pending) {
-               if (up->pending == AF_INET)
+       if (READ_ONCE(up->pending)) {
+               if (READ_ONCE(up->pending) == AF_INET)
                        return udp_sendmsg(sk, msg, len);
                /*
                 * There are pending frames.
@@ -1591,7 +1591,7 @@ back_from_confirm:
                goto out;
        }
 
-       up->pending = AF_INET6;
+       WRITE_ONCE(up->pending, AF_INET6);
 
 do_append_data:
        if (ipc6.dontfrag < 0)
@@ -1605,7 +1605,7 @@ do_append_data:
        else if (!corkreq)
                err = udp_v6_push_pending_frames(sk);
        else if (unlikely(skb_queue_empty(&sk->sk_write_queue)))
-               up->pending = 0;
+               WRITE_ONCE(up->pending, 0);
 
        if (err > 0)
                err = np->recverr ? net_xmit_errno(err) : 0;
@@ -1646,7 +1646,7 @@ static void udpv6_splice_eof(struct socket *sock)
        struct sock *sk = sock->sk;
        struct udp_sock *up = udp_sk(sk);
 
-       if (!up->pending || udp_test_bit(CORK, sk))
+       if (!READ_ONCE(up->pending) || udp_test_bit(CORK, sk))
                return;
 
        lock_sock(sk);