From nobody Sun Nov 24 23:39:32 2024 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A1A00199FB8; Thu, 31 Oct 2024 12:06:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.187 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730376398; cv=none; b=nQX3IwVxiouKcZeb8XWlUMPQQbe4xQRc3Euv6/zT7o8LRF0U63hQWXmBfJm0BBm0WE8l5x0dSBE/PCC3RVXqzXUeoxDLVFDP/cx8kN+3AsYSes79vRbPagZKMPW5SZgomXz/FS9b8mqlmXsJ0o0DX8U+qonIAj6pNM9Fd9BfAzM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730376398; c=relaxed/simple; bh=5sZBGAZdlZ8njThROCJogtID/PIdkdvJbFc6hdanMog=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=Hp3ON8TRdRb2e1ui1H6i+lK5ZLQkzQpDhdQNF6CzzNgfrPHQIL1XkD5BND3XgXJjVXKHscpM2x8zjP1aLk2aLYUpwd3MTTOxJvp4Sc/W5KTT+a1Wzh2carNQrJLvFlGJQ++7ywuTl3G00rzUAt/FIiuD0IT7J8PjXDZQ4lQgMkQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.252]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4XfN2V3MTFz10Mxm; Thu, 31 Oct 2024 20:04:18 +0800 (CST) Received: from kwepemg200005.china.huawei.com (unknown [7.202.181.32]) by mail.maildlp.com (Postfix) with ESMTPS id EBF341800DB; Thu, 31 Oct 2024 20:06:30 +0800 (CST) Received: from huawei.com (10.175.101.6) by kwepemg200005.china.huawei.com (7.202.181.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 31 Oct 2024 20:06:29 +0800 From: Wang Liang To: , , , , , CC: , , , , Subject: [RFC PATCH net] net: fix data-races around sk->sk_forward_alloc Date: Thu, 31 Oct 2024 20:23:44 +0800 Message-ID: <20241031122344.2148586-1-wangliang74@huawei.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemg200005.china.huawei.com (7.202.181.32) Content-Type: text/plain; charset="utf-8" Syzkaller reported this warning: [ 65.568203][ C0] ------------[ cut here ]------------ [ 65.569339][ C0] WARNING: CPU: 0 PID: 16 at net/ipv4/af_inet.c:156 in= et_sock_destruct+0x1c5/0x1e0 [ 65.575017][ C0] Modules linked in: [ 65.575699][ C0] CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted = 6.12.0-rc5 #26 [ 65.577086][ C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996= ), BIOS 1.15.0-1 04/01/2014 [ 65.577094][ C0] RIP: 0010:inet_sock_destruct+0x1c5/0x1e0 [ 65.577100][ C0] Code: 24 12 4c 89 e2 5b 48 c7 c7 98 ec bb 82 41 5c e= 9 d1 18 17 ff 4c 89 e6 5b 48 c7 c7 d0 ec bb 82 41 5c e9 bf 18 17 ff 0f 0b e= b 83 <0f> 0b eb 97 0f 0b eb 87 0f 0b e9 68 ff ff ff 66 66 2e 0f 1f 84 00 [ 65.577107][ C0] RSP: 0018:ffffc9000008bd90 EFLAGS: 00010206 [ 65.577113][ C0] RAX: 0000000000000300 RBX: ffff88810b172a90 RCX: 000= 0000000000007 [ 65.577117][ C0] RDX: 0000000000000002 RSI: 0000000000000300 RDI: fff= f88810b172a00 [ 65.577120][ C0] RBP: ffff88810b172a00 R08: ffff888104273c00 R09: 000= 0000000100007 [ 65.577123][ C0] R10: 0000000000020000 R11: 0000000000000006 R12: fff= f88810b172a00 [ 65.577125][ C0] R13: 0000000000000004 R14: 0000000000000000 R15: fff= f888237c31f78 [ 65.577131][ C0] FS: 0000000000000000(0000) GS:ffff888237c00000(0000= ) knlGS:0000000000000000 [ 65.592485][ C0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 65.592489][ C0] CR2: 00007ffc63fecac8 CR3: 000000000342e000 CR4: 000= 00000000006f0 [ 65.592491][ C0] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 000= 0000000000000 [ 65.592492][ C0] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 000= 0000000000400 [ 65.592495][ C0] Call Trace: [ 65.596277][ C0] [ 65.598171][ C0] ? __warn+0x88/0x130 [ 65.598874][ C0] ? inet_sock_destruct+0x1c5/0x1e0 [ 65.598879][ C0] ? report_bug+0x18e/0x1a0 [ 65.598883][ C0] ? handle_bug+0x53/0x90 [ 65.598886][ C0] ? exc_invalid_op+0x18/0x70 [ 65.598888][ C0] ? asm_exc_invalid_op+0x1a/0x20 [ 65.598893][ C0] ? inet_sock_destruct+0x1c5/0x1e0 [ 65.598897][ C0] __sk_destruct+0x2a/0x200 [ 65.604664][ C0] rcu_do_batch+0x1aa/0x530 [ 65.605450][ C0] ? rcu_do_batch+0x13b/0x530 [ 65.605456][ C0] rcu_core+0x159/0x2f0 [ 65.605466][ C0] handle_softirqs+0xd3/0x2b0 [ 65.607689][ C0] ? __pfx_smpboot_thread_fn+0x10/0x10 [ 65.607695][ C0] run_ksoftirqd+0x25/0x30 [ 65.607699][ C0] smpboot_thread_fn+0xdd/0x1d0 [ 65.610152][ C0] kthread+0xd3/0x100 [ 65.610158][ C0] ? __pfx_kthread+0x10/0x10 [ 65.610160][ C0] ret_from_fork+0x34/0x50 [ 65.610170][ C0] ? __pfx_kthread+0x10/0x10 [ 65.610172][ C0] ret_from_fork_asm+0x1a/0x30 [ 65.610181][ C0] [ 65.610182][ C0] ---[ end trace 0000000000000000 ]--- Its possible that two threads call tcp_v6_do_rcv()/sk_forward_alloc_add() concurrently when sk->sk_state =3D=3D TCP_LISTEN with sk->sk_lock unlocked, which triggers a data-race around sk->sk_forward_alloc: tcp_v6_rcv tcp_v6_do_rcv skb_clone_and_charge_r sk_rmem_schedule __sk_mem_schedule sk_forward_alloc_add() skb_set_owner_r sk_mem_charge sk_forward_alloc_add() __kfree_skb skb_release_all skb_release_head_state sock_rfree sk_mem_uncharge sk_forward_alloc_add() sk_mem_reclaim // set local var reclaimable __sk_mem_reclaim sk_forward_alloc_add() In this syzkaller testcase, two threads call tcp_v6_do_rcv() with skb->truesize=3D768, the sk_forward_alloc changes like this: (cpu 1) | (cpu 2) | sk_forward_alloc ... | ... | 0 __sk_mem_schedule() | | +4096 =3D 4096 | __sk_mem_schedule() | +4096 =3D 8192 sk_mem_charge() | | -768 =3D 7424 | sk_mem_charge() | -768 =3D 6656 ... | ... | sk_mem_uncharge() | | +768 =3D 7424 reclaimable=3D7424 | | | sk_mem_uncharge() | +768 =3D 8192 | reclaimable=3D8192 | __sk_mem_reclaim() | | -4096 =3D 4096 | __sk_mem_reclaim() | -8192 =3D -4096 !=3D 0 Add lock around tcp_v6_do_rcv() in tcp_v6_rcv() will have some the performance impacts, only add lock when opt_skb clone occurs. In some scenes, tcp_v6_do_rcv() is embraced by sk->sk_lock, add TCP_SKB_CB(skb)->sk_lock_capability to avoid re-locking. Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets") Signed-off-by: Wang Liang --- include/net/tcp.h | 3 ++- net/ipv6/tcp_ipv6.c | 21 ++++++++++++++++----- 2 files changed, 18 insertions(+), 6 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index d1948d357dad..110a23dda1eb 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -961,7 +961,8 @@ struct tcp_skb_cb { __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ eor:1, /* Is skb MSG_EOR marked? */ has_rxtstamp:1, /* SKB has a RX timestamp */ - unused:5; + sk_lock_capability:1, /* Avoid re-lock flag */ + unused:4; __u32 ack_seq; /* Sequence number ACK'd */ union { struct { diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index d71ab4e1efe1..a1166035fbce 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1588,6 +1588,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *sk= b) struct sk_buff *opt_skb =3D NULL; enum skb_drop_reason reason; struct tcp_sock *tp; + bool sk_lock_flag =3D false; =20 /* Imagine: socket is IPv6. IPv4 packet arrives, goes to IPv4 receive handler and backlogged. @@ -1618,8 +1619,13 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *s= kb) by tcp. Feel free to propose better solution. --ANK (980728) */ - if (np->rxopt.all) + if (np->rxopt.all) { + if (TCP_SKB_CB(skb)->sk_lock_capability) { + sk_lock_flag =3D true; + bh_lock_sock_nested(sk); + } opt_skb =3D skb_clone_and_charge_r(skb, sk); + } =20 if (sk->sk_state =3D=3D TCP_ESTABLISHED) { /* Fast path */ struct dst_entry *dst; @@ -1641,7 +1647,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *sk= b) tcp_rcv_established(sk, skb); if (opt_skb) goto ipv6_pktoptions; - return 0; + goto unlock; } =20 if (tcp_checksum_complete(skb)) @@ -1658,7 +1664,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *sk= b) } if (opt_skb) __kfree_skb(opt_skb); - return 0; + goto unlock; } } else sock_rps_save_rxhash(sk, skb); @@ -1668,7 +1674,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *sk= b) goto reset; if (opt_skb) goto ipv6_pktoptions; - return 0; + goto unlock; =20 reset: tcp_v6_send_reset(sk, skb, sk_rst_convert_drop_reason(reason)); @@ -1676,7 +1682,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *sk= b) if (opt_skb) __kfree_skb(opt_skb); sk_skb_reason_drop(sk, skb, reason); - return 0; + goto unlock; csum_err: reason =3D SKB_DROP_REASON_TCP_CSUM; trace_tcp_bad_csum(skb); @@ -1715,6 +1721,9 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *sk= b) } =20 consume_skb(opt_skb); +unlock: + if (sk_lock_flag) + bh_unlock_sock(sk); return 0; } =20 @@ -1900,7 +1909,9 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff= *skb) skb->dev =3D NULL; =20 if (sk->sk_state =3D=3D TCP_LISTEN) { + TCP_SKB_CB(skb)->sk_lock_capability =3D true; ret =3D tcp_v6_do_rcv(sk, skb); + TCP_SKB_CB(skb)->sk_lock_capability =3D false; goto put_and_return; } =20 --=20 2.34.1