From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7F3632D97A6; Tue, 31 Mar 2026 17:01:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976485; cv=none; b=jHmehf5mlCIHxhU66GvzrQvNYe0bGJkQ+driEiQk7PCaGzkeES6WqUZahoOcqI7HMNAcToG0tNv12Vs6sgYSqXHs8M1xQiIE1qkmiS6PfGm4HvXgIKAn0ikOJDXAFiTa6UFMF/apeuJEsWQGprQ/AHPIL1NX6gNp9uqsG9EIEWE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976485; c=relaxed/simple; bh=hwGBynoRjCKDTchFoVPzUEiGCSmQ+o4GWOGQup8mYI4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TCFZmJ2HEpf6ZkHQ1Nl0fAbG7j0wV6sPZaiyXWoP2t6Av6fZpZiCX1NHnECpRqK0jh9tycQf2zl1a25+04IKl4n1vKbULSocL/1ZRVVGmKi9bxoJLKOhmnYI6JKiiyusz5cSfKUogZn3Vu79hXNRPacd/mbHANgLcEcVl4dgpUg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=s42Jm/4w; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="s42Jm/4w" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FAA3C19423; Tue, 31 Mar 2026 17:01:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774976484; bh=hwGBynoRjCKDTchFoVPzUEiGCSmQ+o4GWOGQup8mYI4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=s42Jm/4wUOIgvIEqffXcz8ZJsmznd3XJbq9i9Kebo+pqJkCvtHFsx+I+2xY6FrsRC RTKM2yP5nUD31kb8OgXxl5mih0ugpoFQdYBHMHLs2jRQkXhUvnE329Y6KbpqwRHCrS V5ujLYLf4p5J+IE0r5vj6zy0xbnSsHlx9lRkQsCI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrew Onyshchuk , Martin KaFai Lau , Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 111/309] udp: Fix wildcard bind conflict check when using hash2 Date: Tue, 31 Mar 2026 18:20:14 +0200 Message-ID: <20260331161757.571637358@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260331161753.468533260@linuxfoundation.org> References: <20260331161753.468533260@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Martin KaFai Lau [ Upstream commit e537dd15d0d4ad989d56a1021290f0c674dd8b28 ] When binding a udp_sock to a local address and port, UDP uses two hashes (udptable->hash and udptable->hash2) for collision detection. The current code switches to "hash2" when hslot->count > 10. "hash2" is keyed by local address and local port. "hash" is keyed by local port only. The issue can be shown in the following bind sequence (pseudo code): bind(fd1, "[fd00::1]:8888") bind(fd2, "[fd00::2]:8888") bind(fd3, "[fd00::3]:8888") bind(fd4, "[fd00::4]:8888") bind(fd5, "[fd00::5]:8888") bind(fd6, "[fd00::6]:8888") bind(fd7, "[fd00::7]:8888") bind(fd8, "[fd00::8]:8888") bind(fd9, "[fd00::9]:8888") bind(fd10, "[fd00::10]:8888") /* Correctly return -EADDRINUSE because "hash" is used * instead of "hash2". udp_lib_lport_inuse() detects the * conflict. */ bind(fail_fd, "[::]:8888") /* After one more socket is bound to "[fd00::11]:8888", * hslot->count exceeds 10 and "hash2" is used instead. */ bind(fd11, "[fd00::11]:8888") bind(fail_fd, "[::]:8888") /* succeeds unexpectedly */ The same issue applies to the IPv4 wildcard address "0.0.0.0" and the IPv4-mapped wildcard address "::ffff:0.0.0.0". For example, if there are existing sockets bound to "192.168.1.[1-11]:8888", then binding "0.0.0.0:8888" or "[::ffff:0.0.0.0]:8888" can also miss the conflict when hslot->count > 10. TCP inet_csk_get_port() already has the correct check in inet_use_bhash2_on_bind(). Rename it to inet_use_hash2_on_bind() and move it to inet_hashtables.h so udp.c can reuse it in this fix. Fixes: 30fff9231fad ("udp: bind() optimisation") Reported-by: Andrew Onyshchuk Signed-off-by: Martin KaFai Lau Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260319181817.1901357-1-martin.lau@linux.dev Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/inet_hashtables.h | 14 ++++++++++++++ net/ipv4/inet_connection_sock.c | 20 +++----------------- net/ipv4/udp.c | 2 +- 3 files changed, 18 insertions(+), 18 deletions(-) diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index 5a979dcab5383..6d936e9f2fd32 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -264,6 +264,20 @@ inet_bhashfn_portaddr(const struct inet_hashinfo *hinfo, const struct sock *sk, return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)]; } +static inline bool inet_use_hash2_on_bind(const struct sock *sk) +{ +#if IS_ENABLED(CONFIG_IPV6) + if (sk->sk_family == AF_INET6) { + if (ipv6_addr_any(&sk->sk_v6_rcv_saddr)) + return false; + + if (!ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)) + return true; + } +#endif + return sk->sk_rcv_saddr != htonl(INADDR_ANY); +} + struct inet_bind_hashbucket * inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, int port); diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index cdd1e12aac8c0..7a2f116106e96 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -153,20 +153,6 @@ bool inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high) } EXPORT_SYMBOL(inet_sk_get_local_port_range); -static bool inet_use_bhash2_on_bind(const struct sock *sk) -{ -#if IS_ENABLED(CONFIG_IPV6) - if (sk->sk_family == AF_INET6) { - if (ipv6_addr_any(&sk->sk_v6_rcv_saddr)) - return false; - - if (!ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)) - return true; - } -#endif - return sk->sk_rcv_saddr != htonl(INADDR_ANY); -} - static bool inet_bind_conflict(const struct sock *sk, struct sock *sk2, kuid_t uid, bool relax, bool reuseport_cb_ok, bool reuseport_ok) @@ -258,7 +244,7 @@ static int inet_csk_bind_conflict(const struct sock *sk, * checks separately because their spinlocks have to be acquired/released * independently of each other, to prevent possible deadlocks */ - if (inet_use_bhash2_on_bind(sk)) + if (inet_use_hash2_on_bind(sk)) return tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok, reuseport_ok); @@ -375,7 +361,7 @@ inet_csk_find_open_port(const struct sock *sk, struct inet_bind_bucket **tb_ret, head = &hinfo->bhash[inet_bhashfn(net, port, hinfo->bhash_size)]; spin_lock_bh(&head->lock); - if (inet_use_bhash2_on_bind(sk)) { + if (inet_use_hash2_on_bind(sk)) { if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, relax, false)) goto next_port; } @@ -561,7 +547,7 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum) check_bind_conflict = false; } - if (check_bind_conflict && inet_use_bhash2_on_bind(sk)) { + if (check_bind_conflict && inet_use_hash2_on_bind(sk)) { if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, true, true)) goto fail_unlock; } diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 024cb4f5978c1..de0deded74f0a 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -287,7 +287,7 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum, } else { hslot = udp_hashslot(udptable, net, snum); spin_lock_bh(&hslot->lock); - if (hslot->count > 10) { + if (inet_use_hash2_on_bind(sk) && hslot->count > 10) { int exist; unsigned int slot2 = udp_sk(sk)->udp_portaddr_hash ^ snum; -- 2.51.0