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 455ED313E04; Tue, 2 Sep 2025 13:29:18 +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=1756819758; cv=none; b=j9RLYsVq4mgmi2LIej6fUokkdvvRy3+2KIq77x3yxU+2T/h/bn9PVE+I986daubvgF5ZhoSlw/JibHztpM03Bq4Tuwb3c2YrrhGi7vlYCfU/AMc4XKSXMbLxPxuT6HAaM2bc9u30TkYBdiX71IfRn457E1cx63aY5TT7e0EXbUg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756819758; c=relaxed/simple; bh=En3w9yI5fXBjunoeS4Ezr2Ic/mhETn7vfgtO463NMjw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GmELqlObx6ve1endQonrhjSzniYq/lQ/j7Cced+7jnTUvhJkqaiGOzoHyikDsLXqFASTrH6/Foa19qBgbxrQWrfJdsYRtle0yOJwJPHoVhdH9HHBP6n/xLOqr2okGLD0tfL/qZSsfXW1fgZgWwOkW4cwGht7TK1ysbsISvRaey0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tvXAYHG7; 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="tvXAYHG7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6FCBC4CEED; Tue, 2 Sep 2025 13:29:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756819758; bh=En3w9yI5fXBjunoeS4Ezr2Ic/mhETn7vfgtO463NMjw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tvXAYHG7KOeQAwXpDU5+ypz6ekqjIpK4KsTZn8SGj01JP5LuiiICOmZmCAtQFE1kc CA4udVgMyn2z37l3tFYZaM4PSZ6xSVsHVFKTOv6O8V3jnXcPn5V1kJ4BalVHDR6i0w DFquv74oafajCTFTFZ6ZZEas/44YlW19+oqe/vGI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , James Chapman , Guillaume Nault , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.16 098/142] l2tp: do not use sock_hold() in pppol2tp_session_get_sock() Date: Tue, 2 Sep 2025 15:20:00 +0200 Message-ID: <20250902131952.026445742@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250902131948.154194162@linuxfoundation.org> References: <20250902131948.154194162@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 9b8c88f875c04d4cb9111bd5dd9291c7e9691bf5 ] pppol2tp_session_get_sock() is using RCU, it must be ready for sk_refcnt being zero. Commit ee40fb2e1eb5 ("l2tp: protect sock pointer of struct pppol2tp_session with RCU") was correct because it had a call_rcu(..., pppol2tp_put_sk) which was later removed in blamed commit. pppol2tp_recv() can use pppol2tp_session_get_sock() as well. Fixes: c5cbaef992d6 ("l2tp: refactor ppp socket/session relationship") Signed-off-by: Eric Dumazet Cc: James Chapman Reviewed-by: Guillaume Nault Link: https://patch.msgid.link/20250826134435.1683435-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/l2tp/l2tp_ppp.c | 25 ++++++++----------------- 1 file changed, 8 insertions(+), 17 deletions(-) diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index fc5c2fd8f34c7..5e12e7ce17d8a 100644 --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -129,22 +129,12 @@ static const struct ppp_channel_ops pppol2tp_chan_ops = { static const struct proto_ops pppol2tp_ops; -/* Retrieves the pppol2tp socket associated to a session. - * A reference is held on the returned socket, so this function must be paired - * with sock_put(). - */ +/* Retrieves the pppol2tp socket associated to a session. */ static struct sock *pppol2tp_session_get_sock(struct l2tp_session *session) { struct pppol2tp_session *ps = l2tp_session_priv(session); - struct sock *sk; - - rcu_read_lock(); - sk = rcu_dereference(ps->sk); - if (sk) - sock_hold(sk); - rcu_read_unlock(); - return sk; + return rcu_dereference(ps->sk); } /* Helpers to obtain tunnel/session contexts from sockets. @@ -206,14 +196,13 @@ static int pppol2tp_recvmsg(struct socket *sock, struct msghdr *msg, static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len) { - struct pppol2tp_session *ps = l2tp_session_priv(session); - struct sock *sk = NULL; + struct sock *sk; /* If the socket is bound, send it in to PPP's input queue. Otherwise * queue it on the session socket. */ rcu_read_lock(); - sk = rcu_dereference(ps->sk); + sk = pppol2tp_session_get_sock(session); if (!sk) goto no_sock; @@ -510,13 +499,14 @@ static void pppol2tp_show(struct seq_file *m, void *arg) struct l2tp_session *session = arg; struct sock *sk; + rcu_read_lock(); sk = pppol2tp_session_get_sock(session); if (sk) { struct pppox_sock *po = pppox_sk(sk); seq_printf(m, " interface %s\n", ppp_dev_name(&po->chan)); - sock_put(sk); } + rcu_read_unlock(); } static void pppol2tp_session_init(struct l2tp_session *session) @@ -1530,6 +1520,7 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v) port = ntohs(inet->inet_sport); } + rcu_read_lock(); sk = pppol2tp_session_get_sock(session); if (sk) { state = sk->sk_state; @@ -1565,8 +1556,8 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v) struct pppox_sock *po = pppox_sk(sk); seq_printf(m, " interface %s\n", ppp_dev_name(&po->chan)); - sock_put(sk); } + rcu_read_unlock(); } static int pppol2tp_seq_show(struct seq_file *m, void *v) -- 2.50.1