6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ 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 --- net/ipv4/udp.c | 12 ++++++------ net/ipv6/udp.c | 16 ++++++++-------- 2 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index c3ff984b6354..bd12a7658213 100644 --- 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 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) 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 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) 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 f60ba4295435..f1170dcc21d9 100644 --- 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 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) 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 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) goto out; }
- up->pending = AF_INET6; + WRITE_ONCE(up->pending, AF_INET6);
do_append_data: if (ipc6.dontfrag < 0) @@ -1605,7 +1605,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) 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);