netdev - [PATCH net-next 04/10] udp: move udp->gro_enabled to udp->udp

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Date: Tue, 12 Sep 2023 09:17:24 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, Willem de Bruijn <willemdebruijn.kernel@...il.com>, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>, 
	syzbot <syzkaller@...glegroups.com>
Subject: [PATCH net-next 04/10] udp: move udp->gro_enabled to udp->udp_flags

syzbot reported that udp->gro_enabled can be read locklessly.
Use one atomic bit from udp->udp_flags.

Fixes: e20cf8d3f1f7 ("udp: implement GRO for plain UDP sockets.")
Reported-by: syzbot <syzkaller@...glegroups.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/linux/udp.h    | 2 +-
 net/ipv4/udp.c         | 6 +++---
 net/ipv4/udp_offload.c | 4 ++--
 net/ipv6/udp.c         | 2 +-
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 8d4c3835b1b219da9c830f53f09aa0511840a1d4..b344bd2e41fc9f4abf953c29c644b11438b0057d 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -36,6 +36,7 @@ enum {
 	UDP_FLAGS_CORK,		/* Cork is required */
 	UDP_FLAGS_NO_CHECK6_TX, /* Send zero UDP6 checksums on TX? */
 	UDP_FLAGS_NO_CHECK6_RX, /* Allow zero UDP6 checksums on RX? */
+	UDP_FLAGS_GRO_ENABLED,	/* Request GRO aggregation */
 };
 
 struct udp_sock {
@@ -54,7 +55,6 @@ struct udp_sock {
 					   * different encapsulation layer set
 					   * this
 					   */
-			 gro_enabled:1,	/* Request GRO aggregation */
 			 accept_udp_l4:1,
 			 accept_udp_fraglist:1;
 /* indicator bits used by pcflag: */
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index cb32826a1db20006ce9c21e66a9347f41b228da2..1debc10a0f029e47ffe90aaff60727b6bb7309cc 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1868,7 +1868,7 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags,
 						      (struct sockaddr *)sin);
 	}
 
-	if (udp_sk(sk)->gro_enabled)
+	if (udp_test_bit(GRO_ENABLED, sk))
 		udp_cmsg_recv(msg, sk, skb);
 
 	if (inet_cmsg_flags(inet))
@@ -2713,7 +2713,7 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
 		/* when enabling GRO, accept the related GSO packet type */
 		if (valbool)
 			udp_tunnel_encap_enable(sk->sk_socket);
-		up->gro_enabled = valbool;
+		udp_assign_bit(GRO_ENABLED, sk, valbool);
 		up->accept_udp_l4 = valbool;
 		release_sock(sk);
 		break;
@@ -2803,7 +2803,7 @@ int udp_lib_getsockopt(struct sock *sk, int level, int optname,
 		break;
 
 	case UDP_GRO:
-		val = up->gro_enabled;
+		val = udp_test_bit(GRO_ENABLED, sk);
 		break;
 
 	/* The following two cannot be changed on UDP sockets, the return is
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 0f46b3c2e4ac5427a5d39586086048afe22f34f1..6c95d28d0c4a7e56d587a986113b3711f8de964c 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -557,10 +557,10 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
 	NAPI_GRO_CB(skb)->is_flist = 0;
 	if (!sk || !udp_sk(sk)->gro_receive) {
 		if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
-			NAPI_GRO_CB(skb)->is_flist = sk ? !udp_sk(sk)->gro_enabled : 1;
+			NAPI_GRO_CB(skb)->is_flist = sk ? !udp_test_bit(GRO_ENABLED, sk) : 1;
 
 		if ((!sk && (skb->dev->features & NETIF_F_GRO_UDP_FWD)) ||
-		    (sk && udp_sk(sk)->gro_enabled) || NAPI_GRO_CB(skb)->is_flist)
+		    (sk && udp_test_bit(GRO_ENABLED, sk)) || NAPI_GRO_CB(skb)->is_flist)
 			return call_gro_receive(udp_gro_receive_segment, head, skb);
 
 		/* no GRO, be sure flush the current packet */
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 6e1ea3029260ec6e4992cf7e01c0202fabd94017..2c3281879b6dfdf04bf219cf9b13c1c59f732a0d 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -413,7 +413,7 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 						      (struct sockaddr *)sin6);
 	}
 
-	if (udp_sk(sk)->gro_enabled)
+	if (udp_test_bit(GRO_ENABLED, sk))
 		udp_cmsg_recv(msg, sk, skb);
 
 	if (np->rxopt.all)
-- 
2.42.0.283.g2d96d420d3-goog