6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit 70a36f571362a8de8b8c02d21ae524fc776287f2 ]
syzbot/KCSAN complained about UDP_ENCAP_L2TPINUDP setsockopt() racing.
Add READ_ONCE()/WRITE_ONCE() to document races on this lockless field.
syzbot report was: BUG: KCSAN: data-race in udp_lib_setsockopt / udp_lib_setsockopt
read-write to 0xffff8881083603fa of 1 bytes by task 16557 on cpu 0: udp_lib_setsockopt+0x682/0x6c0 udp_setsockopt+0x73/0xa0 net/ipv4/udp.c:2779 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697 __sys_setsockopt+0x1c9/0x230 net/socket.c:2263 __do_sys_setsockopt net/socket.c:2274 [inline] __se_sys_setsockopt net/socket.c:2271 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2271 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
read-write to 0xffff8881083603fa of 1 bytes by task 16554 on cpu 1: udp_lib_setsockopt+0x682/0x6c0 udp_setsockopt+0x73/0xa0 net/ipv4/udp.c:2779 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697 __sys_setsockopt+0x1c9/0x230 net/socket.c:2263 __do_sys_setsockopt net/socket.c:2274 [inline] __se_sys_setsockopt net/socket.c:2271 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2271 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
value changed: 0x01 -> 0x05
Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 16554 Comm: syz-executor.5 Not tainted 6.5.0-rc7-syzkaller-00004-gf7757129e3de #0
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Willem de Bruijn willemb@google.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/gtp.c | 4 ++-- net/ipv4/udp.c | 9 +++++---- net/ipv4/xfrm4_input.c | 4 ++-- net/ipv6/udp.c | 5 +++-- net/ipv6/xfrm6_input.c | 4 ++-- net/l2tp/l2tp_core.c | 6 +++--- 6 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 477b4d4f860bd..bace989591f75 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -629,7 +629,7 @@ static void __gtp_encap_destroy(struct sock *sk) gtp->sk0 = NULL; else gtp->sk1u = NULL; - udp_sk(sk)->encap_type = 0; + WRITE_ONCE(udp_sk(sk)->encap_type, 0); rcu_assign_sk_user_data(sk, NULL); release_sock(sk); sock_put(sk); @@ -681,7 +681,7 @@ static int gtp_encap_recv(struct sock *sk, struct sk_buff *skb)
netdev_dbg(gtp->dev, "encap_recv sk=%p\n", sk);
- switch (udp_sk(sk)->encap_type) { + switch (READ_ONCE(udp_sk(sk)->encap_type)) { case UDP_ENCAP_GTP0: netdev_dbg(gtp->dev, "received GTP0 packet\n"); ret = gtp0_udp_encap_recv(gtp, skb); diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 267f77633a8f3..5672d9a86c5d2 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -733,7 +733,7 @@ int __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable) iph->saddr, uh->source, skb->dev->ifindex, inet_sdif(skb), udptable, NULL);
- if (!sk || udp_sk(sk)->encap_type) { + if (!sk || READ_ONCE(udp_sk(sk)->encap_type)) { /* No socket for error: try tunnels before discarding */ if (static_branch_unlikely(&udp_encap_needed_key)) { sk = __udp4_lib_err_encap(net, iph, uh, udptable, sk, skb, @@ -2114,7 +2114,8 @@ static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb) } nf_reset_ct(skb);
- if (static_branch_unlikely(&udp_encap_needed_key) && up->encap_type) { + if (static_branch_unlikely(&udp_encap_needed_key) && + READ_ONCE(up->encap_type)) { int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
/* @@ -2699,7 +2700,7 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname, #endif fallthrough; case UDP_ENCAP_L2TPINUDP: - up->encap_type = val; + WRITE_ONCE(up->encap_type, val); udp_tunnel_encap_enable(sk); break; default: @@ -2800,7 +2801,7 @@ int udp_lib_getsockopt(struct sock *sk, int level, int optname, break;
case UDP_ENCAP: - val = up->encap_type; + val = READ_ONCE(up->encap_type); break;
case UDP_NO_CHECK6_TX: diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c index eac206a290d05..183f6dc372429 100644 --- a/net/ipv4/xfrm4_input.c +++ b/net/ipv4/xfrm4_input.c @@ -85,11 +85,11 @@ int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb) struct udphdr *uh; struct iphdr *iph; int iphlen, len; - __u8 *udpdata; __be32 *udpdata32; - __u16 encap_type = up->encap_type; + u16 encap_type;
+ encap_type = READ_ONCE(up->encap_type); /* if this is not encapsulated socket, then just return now */ if (!encap_type) return 1; diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 5b7c4f8e2ed03..961106eda69d0 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -598,7 +598,7 @@ int __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt, sk = __udp6_lib_lookup(net, daddr, uh->dest, saddr, uh->source, inet6_iif(skb), inet6_sdif(skb), udptable, NULL);
- if (!sk || udp_sk(sk)->encap_type) { + if (!sk || READ_ONCE(udp_sk(sk)->encap_type)) { /* No socket for error: try tunnels before discarding */ if (static_branch_unlikely(&udpv6_encap_needed_key)) { sk = __udp6_lib_err_encap(net, hdr, offset, uh, @@ -712,7 +712,8 @@ static int udpv6_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb) } nf_reset_ct(skb);
- if (static_branch_unlikely(&udpv6_encap_needed_key) && up->encap_type) { + if (static_branch_unlikely(&udpv6_encap_needed_key) && + READ_ONCE(up->encap_type)) { int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
/* diff --git a/net/ipv6/xfrm6_input.c b/net/ipv6/xfrm6_input.c index 4907ab241d6be..4156387248e40 100644 --- a/net/ipv6/xfrm6_input.c +++ b/net/ipv6/xfrm6_input.c @@ -81,14 +81,14 @@ int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb) struct ipv6hdr *ip6h; int len; int ip6hlen = sizeof(struct ipv6hdr); - __u8 *udpdata; __be32 *udpdata32; - __u16 encap_type = up->encap_type; + u16 encap_type;
if (skb->protocol == htons(ETH_P_IP)) return xfrm4_udp_encap_rcv(sk, skb);
+ encap_type = READ_ONCE(up->encap_type); /* if this is not encapsulated socket, then just return now */ if (!encap_type) return 1; diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 03608d3ded4b8..8d21ff25f1602 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1139,9 +1139,9 @@ static void l2tp_tunnel_destruct(struct sock *sk) switch (tunnel->encap) { case L2TP_ENCAPTYPE_UDP: /* No longer an encapsulation socket. See net/ipv4/udp.c */ - (udp_sk(sk))->encap_type = 0; - (udp_sk(sk))->encap_rcv = NULL; - (udp_sk(sk))->encap_destroy = NULL; + WRITE_ONCE(udp_sk(sk)->encap_type, 0); + udp_sk(sk)->encap_rcv = NULL; + udp_sk(sk)->encap_destroy = NULL; break; case L2TP_ENCAPTYPE_IP: break;