This is a note to let you know that I've just added the patch titled
udp: annotate data-races around udp->encap_type
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
udp-annotate-data-races-around-udp-encap_type.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 869b993b09a4c3402014db8c128bbea82ce5f26f
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Tue Sep 12 09:17:28 2023 +0000
udp: annotate data-races around udp->encap_type
[ 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@xxxxxxxxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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 4df99839e7a30..be0370a64cc15 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -744,7 +744,7 @@ 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,
@@ -2110,7 +2110,8 @@ 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);
/*
@@ -2709,7 +2710,7 @@ 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:
@@ -2810,7 +2811,7 @@ 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 4f39511bb0969..9988160ca4a76 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -604,7 +604,7 @@ 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,
@@ -721,7 +721,8 @@ 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;
