From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [95.215.58.180]) (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 D2CE41F4613 for ; Wed, 24 Sep 2025 01:52:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758678724; cv=none; b=uFsCkt0eDzox8rjCLIBMP2nfFskeAMDTAR2xZ+fCAK2xE0CWZNeLayhyfBAxBZR8F6YEYw8RtEo8YjDOTFQG2mF9wy+fayRce84GszySUoD8b6LTId1nLhwq2oqOGdiewhD2ujvZ0SEwlD92zyH1bUDy7JmKM5krgR49VVPheVA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758678724; c=relaxed/simple; bh=rYaK0EPR8EdrBdtIJtTxXNoXZ5YnMFg+gEh2J9oBdKw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Cbh4R9cZHYS7BW5r15jFS4Ukuim60uIIJsnv6QrsFNR56rdP5/yGyst3cryKbI8cWxYcVmIIQdRzi0aVamxm6u/O3ByXye/KoaE1FiyQ5/j1475Eyp9BeoCdoqfL9uQoxfxEUCzjyGqNTIU2lYK507NUM3Wv2aoTB+nvmWzjve4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=soRawyNB; arc=none smtp.client-ip=95.215.58.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="soRawyNB" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1758678721; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=08cYPk4H+4tGivGG309edyzN/dObOcHEihkD9Vlpn4s=; b=soRawyNBpeDgZ+3B85Gr1FPKtF3/2KR+zansTbMLRZ3d7obUOTgFvVgQVqfZeA5Eu74Jy4 F2ivfxyC6UPA5gTMtRmBUoXSIBegtA93ZeBcskiHYSpXZLyQg/UCU2sUvoN1HU9XJOG3q1 jmFqn2obV2USG8eAXnS3lfGjhzmcW5Y= From: xuanqiang.luo@linux.dev To: edumazet@google.com, kuniyu@google.com Cc: kerneljasonxing@gmail.com, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, Xuanqiang Luo Subject: [PATCH net-next v5 2/3] inet: Avoid ehash lookup race in inet_ehash_insert() Date: Wed, 24 Sep 2025 09:50:33 +0800 Message-Id: <20250924015034.587056-3-xuanqiang.luo@linux.dev> In-Reply-To: <20250924015034.587056-1-xuanqiang.luo@linux.dev> References: <20250924015034.587056-1-xuanqiang.luo@linux.dev> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Xuanqiang Luo Since ehash lookups are lockless, if one CPU performs a lookup while another concurrently deletes and inserts (removing reqsk and inserting sk), the lookup may fail to find the socket, an RST may be sent. The call trace map is drawn as follows: CPU 0 CPU 1 ----- ----- inet_ehash_insert() spin_lock() sk_nulls_del_node_init_rcu(osk) __inet_lookup_established() (lookup failed) __sk_nulls_add_node_rcu(sk, list) spin_unlock() As both deletion and insertion operate on the same ehash chain, this patch introduces a new sk_nulls_replace_node_init_rcu() helper functions to implement atomic replacement. Fixes: 5e0724d027f0 ("tcp/dccp: fix hashdance race for passive sessions") Signed-off-by: Xuanqiang Luo --- include/net/sock.h | 14 ++++++++++++++ net/ipv4/inet_hashtables.c | 4 +++- 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/include/net/sock.h b/include/net/sock.h index 0fd465935334..5d67f5cbae52 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -854,6 +854,20 @@ static inline bool sk_nulls_del_node_init_rcu(struct sock *sk) return rc; } +static inline bool sk_nulls_replace_node_init_rcu(struct sock *old, + struct sock *new) +{ + if (sk_hashed(old)) { + hlist_nulls_replace_init_rcu(&old->sk_nulls_node, + &new->sk_nulls_node); + DEBUG_NET_WARN_ON_ONCE(refcount_read(&old->sk_refcnt) == 1); + __sock_put(old); + return true; + } + + return false; +} + static inline void __sk_add_node(struct sock *sk, struct hlist_head *list) { hlist_add_head(&sk->sk_node, list); diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index ef4ccfd46ff6..83c9ec625419 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -685,7 +685,8 @@ bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk) spin_lock(lock); if (osk) { WARN_ON_ONCE(sk->sk_hash != osk->sk_hash); - ret = sk_nulls_del_node_init_rcu(osk); + ret = sk_nulls_replace_node_init_rcu(osk, sk); + goto unlock; } else if (found_dup_sk) { *found_dup_sk = inet_ehash_lookup_by_sk(sk, list); if (*found_dup_sk) @@ -695,6 +696,7 @@ bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk) if (ret) __sk_nulls_add_node_rcu(sk, list); +unlock: spin_unlock(lock); return ret; -- 2.25.1