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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Florian Westphal , Kishen Maloor , Shuah Khan , Peter Krystad , Christoph Paasch Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, "Matthieu Baerts (NGI0)" , stable@vger.kernel.org X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5011; i=matttbe@kernel.org; h=from:subject:message-id; bh=r5yS2aqxy/UFqDVBdC2SzLwUgEbcbOAGxz23X5YQglQ=; b=owEBbQKS/ZANAwAIAfa3gk9CaaBzAcsmYgBl2MRqJQlYEbverqjk/Wt3czNkvGndu41GkjAVk Ipdmg1TyUyJAjMEAAEIAB0WIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZdjEagAKCRD2t4JPQmmg c+qAD/9eH6iHyK1RwTYjxr/tAoH+SjQQWyyiQhjuZRa5eOHb/Wzp9QHInrYQhEAcrT2McZ/qBia ngOUSBp9kzlnuljowjUa2wDCVqhW+RE11BWvUqSHvvtONFt9HBxzyQ2RLSHLkFB/2ZMPqbUca8L 2Oot9QjYxQQrCUex4NzQkNiQNlleaTChQpPDUmU6AwaVeVvf1C9d7w9rQxA1rV2BSHNa4C2jsgu JXZY+424zLdFx3MnM0cW6IhfkrK8D+zquFuViCGyh3Tzkp7s3UlnumO48JCcucLouAyb3o2a2e4 AWCzqLcxCoeten7eVvogMlPV+wFQwnEC2S2LbKgD91eXBQot4KqoBcvXm2W5bwO6ScSYfT2HJ5q bihP/eSvTpdtNN2XlqarlQqC1ccgxKOm7x4LiXwm4BPnNgOBOWtKVFKrXumFB7bcgt8DEfJ4GfZ osl8rwV73RgwfLCOJX+Iunv2dYGwXKnbNEB9paFifPw2SsqeXwdwDDl23h5HDb6PlDJ0vLvKSqW 6tQ+r3siPX5XS7MTyTS0mlYNd3pw6v/BoN5q76wIUJbJtdO7w7iUfGUD/LtCwERJIvZs0edULIu hM0WLZ4gVlGgw2YyESGr+HphdIbVLsk/TKEtc4oRBXRajGJf8rapMqw4BaVQRrnM+lFzJIdRSBB 4lKYfuJ0BLEbuMw== X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 From: Paolo Abeni Syzbot and Eric reported a lockdep splat in the subflow diag: WARNING: possible circular locking dependency detected 6.8.0-rc4-syzkaller-00212-g40b9385dd8e6 #0 Not tainted syz-executor.2/24141 is trying to acquire lock: ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_diag_put_ulp net/ipv4/tcp_diag.c:100 [inline] ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_diag_get_aux+0x738/0x830 net/ipv4/tcp_diag.c:137 but task is already holding lock: ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at: inet_diag_dump_icsk+0x39f/0x1f80 net/ipv4/inet_diag.c:1038 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&h->lhash2[i].lock){+.+.}-{2:2}: lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __inet_hash+0x335/0xbe0 net/ipv4/inet_hashtables.c:743 inet_csk_listen_start+0x23a/0x320 net/ipv4/inet_connection_sock.c:1261 __inet_listen_sk+0x2a2/0x770 net/ipv4/af_inet.c:217 inet_listen+0xa3/0x110 net/ipv4/af_inet.c:239 rds_tcp_listen_init+0x3fd/0x5a0 net/rds/tcp_listen.c:316 rds_tcp_init_net+0x141/0x320 net/rds/tcp.c:577 ops_init+0x352/0x610 net/core/net_namespace.c:136 __register_pernet_operations net/core/net_namespace.c:1214 [inline] register_pernet_operations+0x2cb/0x660 net/core/net_namespace.c:1283 register_pernet_device+0x33/0x80 net/core/net_namespace.c:1370 rds_tcp_init+0x62/0xd0 net/rds/tcp.c:735 do_one_initcall+0x238/0x830 init/main.c:1236 do_initcall_level+0x157/0x210 init/main.c:1298 do_initcalls+0x3f/0x80 init/main.c:1314 kernel_init_freeable+0x42f/0x5d0 init/main.c:1551 kernel_init+0x1d/0x2a0 init/main.c:1441 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242 -> #0 (k-sk_lock-AF_INET6){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 lock_sock_fast include/net/sock.h:1723 [inline] subflow_get_info+0x166/0xd20 net/mptcp/diag.c:28 tcp_diag_put_ulp net/ipv4/tcp_diag.c:100 [inline] tcp_diag_get_aux+0x738/0x830 net/ipv4/tcp_diag.c:137 inet_sk_diag_fill+0x10ed/0x1e00 net/ipv4/inet_diag.c:345 inet_diag_dump_icsk+0x55b/0x1f80 net/ipv4/inet_diag.c:1061 __inet_diag_dump+0x211/0x3a0 net/ipv4/inet_diag.c:1263 inet_diag_dump_compat+0x1c1/0x2d0 net/ipv4/inet_diag.c:1371 netlink_dump+0x59b/0xc80 net/netlink/af_netlink.c:2264 __netlink_dump_start+0x5df/0x790 net/netlink/af_netlink.c:2370 netlink_dump_start include/linux/netlink.h:338 [inline] inet_diag_rcv_msg_compat+0x209/0x4c0 net/ipv4/inet_diag.c:1405 sock_diag_rcv_msg+0xe7/0x410 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2543 sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:280 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline] netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1367 netlink_sendmsg+0xa3b/0xd70 net/netlink/af_netlink.c:1908 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 As noted by Eric we can break the lock dependency chain avoid dumping any extended info for the mptcp subflow listener: nothing actually useful is presented there. Fixes: b8adb69a7d29 ("mptcp: fix lockless access in subflow ULP diag") Cc: stable@vger.kernel.org Reported-by: Eric Dumazet Closes: https://lore.kernel.org/netdev/CANn89iJ=Oecw6OZDwmSYc9HJKQ_G32uN11L+oUcMu+TOD5Xiaw@mail.gmail.com/ Suggested-by: Eric Dumazet Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) --- net/mptcp/diag.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c index 6ff6f14674aa..7017dd60659d 100644 --- a/net/mptcp/diag.c +++ b/net/mptcp/diag.c @@ -21,6 +21,9 @@ static int subflow_get_info(struct sock *sk, struct sk_buff *skb) bool slow; int err; + if (inet_sk_state_load(sk) == TCP_LISTEN) + return 0; + start = nla_nest_start_noflag(skb, INET_ULP_INFO_MPTCP); if (!start) return -EMSGSIZE; -- 2.43.0