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 33E6E78B7C; Wed, 21 Feb 2024 13:51:28 +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=1708523488; cv=none; b=Q1y5fca0xhBSk2s21BUm4aP8cApv0VpiMvbAT/le3kDHMZwABW3BTuWsCGsPzkTitUzAiN60my3hgWC591u/giJ8zqnIN6IsLiGBtILej9EXH1RJCvE003rLVN9L+r9aA9WwGOYPQ8R9pN8e3tilK8ip+1uY45job6VxDjf0MNo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708523488; c=relaxed/simple; bh=6oHrQiD3DRlv5OvTanFYdpIjhG7h+tLdmBqDKnrOuaY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PuZ57in+QGwZky5kt/f4Lq5MkXoOlW1KoqftbFP7qzre5PaghZvPBCEZ1sp3HseJ2qFT7N8PMoP0CxCX5o7sh79gM3mX5oYwrAlooZ07LEMCCNcVq/+JxvV5Ki16tEmyemrOQyL0nFGFO38iiEo8IuukQPu+ziseNH5l0WUnpFM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=nEb4ECnC; 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="nEb4ECnC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B03DFC433C7; Wed, 21 Feb 2024 13:51:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1708523488; bh=6oHrQiD3DRlv5OvTanFYdpIjhG7h+tLdmBqDKnrOuaY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nEb4ECnCj6dUp4qlltOO/ZOq9HMeZM+uNvKtFq2lvWT6GfaLUAwMTP5hwyJIni2uR gTrCh/aUdEAFRzd1vBAVIYwv5fklrb+qF2fa/capw9GE1iy1I9VVvwkgu0Y3/tOBgf ylvh6h1AVjduu14omMF8JV732ONGyaX8DCjQ/AcQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+1591462f226d9cbf0564@syzkaller.appspotmail.com, Ziqi Zhao , Oleksij Rempel , Marc Kleine-Budde Subject: [PATCH 5.15 421/476] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock Date: Wed, 21 Feb 2024 14:07:52 +0100 Message-ID: <20240221130023.603027199@linuxfoundation.org> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240221130007.738356493@linuxfoundation.org> References: <20240221130007.738356493@linuxfoundation.org> User-Agent: quilt/0.67 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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ziqi Zhao commit 6cdedc18ba7b9dacc36466e27e3267d201948c8d upstream. The following 3 locks would race against each other, causing the deadlock situation in the Syzbot bug report: - j1939_socks_lock - active_session_list_lock - sk_session_queue_lock A reasonable fix is to change j1939_socks_lock to an rwlock, since in the rare situations where a write lock is required for the linked list that j1939_socks_lock is protecting, the code does not attempt to acquire any more locks. This would break the circular lock dependency, where, for example, the current thread already locks j1939_socks_lock and attempts to acquire sk_session_queue_lock, and at the same time, another thread attempts to acquire j1939_socks_lock while holding sk_session_queue_lock. NOTE: This patch along does not fix the unregister_netdevice bug reported by Syzbot; instead, it solves a deadlock situation to prepare for one or more further patches to actually fix the Syzbot bug, which appears to be a reference counting problem within the j1939 codebase. Reported-by: Signed-off-by: Ziqi Zhao Reviewed-by: Oleksij Rempel Acked-by: Oleksij Rempel Link: https://lore.kernel.org/all/20230721162226.8639-1-astrajoan@yahoo.com [mkl: remove unrelated newline change] Cc: stable@vger.kernel.org Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- net/can/j1939/j1939-priv.h | 2 +- net/can/j1939/main.c | 2 +- net/can/j1939/socket.c | 24 ++++++++++++------------ 3 files changed, 14 insertions(+), 14 deletions(-) --- a/net/can/j1939/j1939-priv.h +++ b/net/can/j1939/j1939-priv.h @@ -86,7 +86,7 @@ struct j1939_priv { unsigned int tp_max_packet_size; /* lock for j1939_socks list */ - spinlock_t j1939_socks_lock; + rwlock_t j1939_socks_lock; struct list_head j1939_socks; struct kref rx_kref; --- a/net/can/j1939/main.c +++ b/net/can/j1939/main.c @@ -270,7 +270,7 @@ struct j1939_priv *j1939_netdev_start(st return ERR_PTR(-ENOMEM); j1939_tp_init(priv); - spin_lock_init(&priv->j1939_socks_lock); + rwlock_init(&priv->j1939_socks_lock); INIT_LIST_HEAD(&priv->j1939_socks); mutex_lock(&j1939_netdev_lock); --- a/net/can/j1939/socket.c +++ b/net/can/j1939/socket.c @@ -80,16 +80,16 @@ static void j1939_jsk_add(struct j1939_p jsk->state |= J1939_SOCK_BOUND; j1939_priv_get(priv); - spin_lock_bh(&priv->j1939_socks_lock); + write_lock_bh(&priv->j1939_socks_lock); list_add_tail(&jsk->list, &priv->j1939_socks); - spin_unlock_bh(&priv->j1939_socks_lock); + write_unlock_bh(&priv->j1939_socks_lock); } static void j1939_jsk_del(struct j1939_priv *priv, struct j1939_sock *jsk) { - spin_lock_bh(&priv->j1939_socks_lock); + write_lock_bh(&priv->j1939_socks_lock); list_del_init(&jsk->list); - spin_unlock_bh(&priv->j1939_socks_lock); + write_unlock_bh(&priv->j1939_socks_lock); j1939_priv_put(priv); jsk->state &= ~J1939_SOCK_BOUND; @@ -329,13 +329,13 @@ bool j1939_sk_recv_match(struct j1939_pr struct j1939_sock *jsk; bool match = false; - spin_lock_bh(&priv->j1939_socks_lock); + read_lock_bh(&priv->j1939_socks_lock); list_for_each_entry(jsk, &priv->j1939_socks, list) { match = j1939_sk_recv_match_one(jsk, skcb); if (match) break; } - spin_unlock_bh(&priv->j1939_socks_lock); + read_unlock_bh(&priv->j1939_socks_lock); return match; } @@ -344,11 +344,11 @@ void j1939_sk_recv(struct j1939_priv *pr { struct j1939_sock *jsk; - spin_lock_bh(&priv->j1939_socks_lock); + read_lock_bh(&priv->j1939_socks_lock); list_for_each_entry(jsk, &priv->j1939_socks, list) { j1939_sk_recv_one(jsk, skb); } - spin_unlock_bh(&priv->j1939_socks_lock); + read_unlock_bh(&priv->j1939_socks_lock); } static void j1939_sk_sock_destruct(struct sock *sk) @@ -1078,12 +1078,12 @@ void j1939_sk_errqueue(struct j1939_sess } /* spread RX notifications to all sockets subscribed to this session */ - spin_lock_bh(&priv->j1939_socks_lock); + read_lock_bh(&priv->j1939_socks_lock); list_for_each_entry(jsk, &priv->j1939_socks, list) { if (j1939_sk_recv_match_one(jsk, &session->skcb)) __j1939_sk_errqueue(session, &jsk->sk, type); } - spin_unlock_bh(&priv->j1939_socks_lock); + read_unlock_bh(&priv->j1939_socks_lock); }; void j1939_sk_send_loop_abort(struct sock *sk, int err) @@ -1271,7 +1271,7 @@ void j1939_sk_netdev_event_netdown(struc struct j1939_sock *jsk; int error_code = ENETDOWN; - spin_lock_bh(&priv->j1939_socks_lock); + read_lock_bh(&priv->j1939_socks_lock); list_for_each_entry(jsk, &priv->j1939_socks, list) { jsk->sk.sk_err = error_code; if (!sock_flag(&jsk->sk, SOCK_DEAD)) @@ -1279,7 +1279,7 @@ void j1939_sk_netdev_event_netdown(struc j1939_sk_queue_drop_all(priv, jsk, error_code); } - spin_unlock_bh(&priv->j1939_socks_lock); + read_unlock_bh(&priv->j1939_socks_lock); } static int j1939_sk_no_ioctlcmd(struct socket *sock, unsigned int cmd,