From nobody Wed Apr 8 00:00:03 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23260C433FE for ; Thu, 20 Oct 2022 13:28:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229972AbiJTN2q (ORCPT ); Thu, 20 Oct 2022 09:28:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36858 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229543AbiJTN2n (ORCPT ); Thu, 20 Oct 2022 09:28:43 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5FF01A1B03; Thu, 20 Oct 2022 06:28:41 -0700 (PDT) Received: from kwepemi500015.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4MtSwn1g4qzmVDF; Thu, 20 Oct 2022 21:23:53 +0800 (CST) Received: from huawei.com (10.175.101.6) by kwepemi500015.china.huawei.com (7.221.188.92) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Thu, 20 Oct 2022 21:28:37 +0800 From: Lu Wei To: , , , , , , , , , , , , , Subject: [PATCH -next,v2] tcp: fix a signed-integer-overflow bug in tcp_add_backlog() Date: Thu, 20 Oct 2022 22:32:01 +0800 Message-ID: <20221020143201.339599-1-luwei32@huawei.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemi500015.china.huawei.com (7.221.188.92) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The type of sk_rcvbuf and sk_sndbuf in struct sock is int, and in tcp_add_backlog(), the variable limit is caculated by adding sk_rcvbuf, sk_sndbuf and 64 * 1024, it may exceed the max value of int and overflow. This patch limits sk_rcvbuf and sk_sndbuf to 0x7fff000 and transfers them to u32 to avoid signed-integer overflow. Fixes: c9c3321257e1 ("tcp: add tcp_add_backlog()") Signed-off-by: Lu Wei --- include/net/sock.h | 5 +++++ net/core/sock.c | 10 ++++++---- net/ipv4/tcp_ipv4.c | 3 ++- 3 files changed, 13 insertions(+), 5 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 9e464f6409a7..cc2d6c4047c2 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2529,6 +2529,11 @@ static inline void sk_wake_async(const struct sock *= sk, int how, int band) #define SOCK_MIN_SNDBUF (TCP_SKB_MIN_TRUESIZE * 2) #define SOCK_MIN_RCVBUF TCP_SKB_MIN_TRUESIZE =20 +/* limit sk_sndbuf and sk_rcvbuf to 0x7fff0000 to prevent overflow + * when adding sk_sndbuf, sk_rcvbuf and 64K in tcp_add_backlog() + */ +#define SOCK_MAX_SNDRCVBUF (INT_MAX - 0xFFFF) + static inline void sk_stream_moderate_sndbuf(struct sock *sk) { u32 val; diff --git a/net/core/sock.c b/net/core/sock.c index a3ba0358c77c..33acc5e71100 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -950,7 +950,7 @@ static void __sock_set_rcvbuf(struct sock *sk, int val) /* Ensure val * 2 fits into an int, to prevent max_t() from treating it * as a negative value. */ - val =3D min_t(int, val, INT_MAX / 2); + val =3D min_t(int, val, SOCK_MAX_SNDRCVBUF / 2); sk->sk_userlocks |=3D SOCK_RCVBUF_LOCK; =20 /* We double it on the way in to account for "struct sk_buff" etc. @@ -1142,7 +1142,7 @@ int sk_setsockopt(struct sock *sk, int level, int opt= name, /* Ensure val * 2 fits into an int, to prevent max_t() * from treating it as a negative value. */ - val =3D min_t(int, val, INT_MAX / 2); + val =3D min_t(int, val, SOCK_MAX_SNDRCVBUF / 2); sk->sk_userlocks |=3D SOCK_SNDBUF_LOCK; WRITE_ONCE(sk->sk_sndbuf, max_t(int, val * 2, SOCK_MIN_SNDBUF)); @@ -3365,8 +3365,10 @@ void sock_init_data(struct socket *sock, struct sock= *sk) timer_setup(&sk->sk_timer, NULL, 0); =20 sk->sk_allocation =3D GFP_KERNEL; - sk->sk_rcvbuf =3D READ_ONCE(sysctl_rmem_default); - sk->sk_sndbuf =3D READ_ONCE(sysctl_wmem_default); + sk->sk_rcvbuf =3D min_t(int, SOCK_MAX_SNDRCVBUF, + READ_ONCE(sysctl_rmem_default)); + sk->sk_sndbuf =3D min_t(int, SOCK_MAX_SNDRCVBUF, + READ_ONCE(sysctl_wmem_default)); sk->sk_state =3D TCP_CLOSE; sk_set_socket(sk, sock); =20 diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 7a250ef9d1b7..5340733336a6 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1878,7 +1878,8 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff = *skb, * to reduce memory overhead, so add a little headroom here. * Few sockets backlog are possibly concurrently non empty. */ - limit =3D READ_ONCE(sk->sk_rcvbuf) + READ_ONCE(sk->sk_sndbuf) + 64*1024; + limit =3D (u32)READ_ONCE(sk->sk_rcvbuf) + + (u32)READ_ONCE(sk->sk_sndbuf) + 64*1024; =20 if (unlikely(sk_add_backlog(sk, skb, limit))) { bh_unlock_sock(sk); --=20 2.31.1