From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-il1-f199.google.com (mail-il1-f199.google.com [209.85.166.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E3F7C22092 for ; Sun, 29 Sep 2024 09:26:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727601990; cv=none; b=CIn3yh+bWpvC9Ap7tnIRR67Pb+GomA/++V+U75FHOzHhegbzuP64utoOxyt8sDuERwTQ+lErcrzM+NauRO+qSmJcIUEL/DR7fR7DtL1euWJoBMs6FFZ4fkIqwNMv4dWR7x+cFrv7q82ZXU0rsdXm0uAtxsMaQu2p19huOd1aBOI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727601990; c=relaxed/simple; bh=IoV4/qXvaw/PKEniiBL+nLujKz/iEoUY3RTYU7vT3TU=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=s6oiHEmS40sO1XBDSQYYzh8OBeXEaB2GEahsNiFhqMMlOdMg2FQY/N1qoDWzq/22SMsXLxqgrr6vrTjZuX294bwe89PhHXMu/CL86vJmD6246P2MqIN3knh4dGPSPwOavCcHRw5wjkUhsGNEw2KYK8P2e4jrNNuDQNKL8iyHq9w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.166.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-il1-f199.google.com with SMTP id e9e14a558f8ab-3a3479460f4so20268655ab.2 for ; Sun, 29 Sep 2024 02:26:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1727601988; x=1728206788; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=p4k4S7F0QcngH584k5Dff8d5BsEwVEVc+07OCGlmuJw=; b=hOowON0R9VQSTh/jWO/rCg+9TP+WXilgcWY0UdjpNY9jBuip+mkkowBOjhzqzh6Bho j5vXSeziU0Pv1D+BKLQjGDVG6Kv9oDqHVDk3okHOwnPmMMVkQc3vB8htn08c8sHhFY57 jIjX9jj6sIeOP3lO+5Gk1waljDR4rxSxGwWc1DUlWcbJe1QYcFEwgZ23+OdKS/DqtF2D HEM/Gotk4k+gHaYtHYBoYVe9diCFmPx+DwV60MznKoU5h2IrFZOrZRAi1gyNothlsJVv 9VFs1XWaV9kDi4xwuJTB0A6Sq4TJDOTdW+aTM/Fs1OhoHW0yALEOpntGyWgDsows6pFC ZzyA== X-Gm-Message-State: AOJu0YxI4JXWKKx7q+DfJtRb6GY+q1pZIpOjxjP5TAvfkVa0lBh9oub5 DsWajp+Fy9i0QfYhG3dHQa953SSo9BsedgaEiDPEMKhxTKybywbEF6rMeBZsbNKn4sQ/PzI3/hF AA59zDwq2Mk5ogshTvr/Ei4qOJIm5crMnIHKCZzsHSD6Qyipot6IjJsQ= X-Google-Smtp-Source: AGHT+IHIhlU6/Xy7BTeB0a+NzmVERjbxKzx4PxxlkgbFvRjcvA3hgLA38niAB/JgFxzEvj20p5r1IQ8K9tKlhuIl8NFCwI8YyPev Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a92:c266:0:b0:3a0:8ecb:a1dc with SMTP id e9e14a558f8ab-3a34517fac8mr70126225ab.15.1727601987997; Sun, 29 Sep 2024 02:26:27 -0700 (PDT) Date: Sun, 29 Sep 2024 02:26:27 -0700 In-Reply-To: <000000000000abe6b50620a7f370@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <66f91d43.050a0220.aab67.0016.GAE@google.com> Subject: Re: [syzbot] Re: [syzbot] [bpf?] [net?] WARNING in sock_map_destroy From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: Re: [syzbot] [bpf?] [net?] WARNING in sock_map_destroy Author: dmantipov@yandex.ru #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 3efc57369a0ce8f76bf0804f7e673982384e4ac9 >From 12b932f214f0caaaa79f929ab81b46ebea125a06 Mon Sep 17 00:00:00 2001 From: Dmitry Antipov Date: Tue, 10 Sep 2024 14:21:20 +0300 Subject: [PATCH net v2] net: sockmap: avoid race between sock_map_destroy() and sk_psock_put() Syzbot has triggered the following race condition: On CPU0, 'sk_psock_drop()' (most likely scheduled from 'sock_map_unref()' called by 'sock_map_update_common()') is running at [1]: void sk_psock_drop(struct sock *sk, struct sk_psock *psock) { write_lock_bh(&sk->sk_callback_lock); sk_psock_restore_proto(sk, psock); [1] rcu_assign_sk_user_data(sk, NULL); [2] ... } If 'sock_map_destroy()' is scheduled on CPU1 at the same time, psock is always NULL at [3]. But, since [1] may be is in progress during [4], the value of 'saved_destroy' at this point is undefined: void sock_map_destroy(struct sock *sk) { void (*saved_destroy)(struct sock *sk); struct sk_psock *psock; rcu_read_lock(); psock = sk_psock_get(sk); [3] if (unlikely(!psock)) { rcu_read_unlock(); saved_destroy = READ_ONCE(sk->sk_prot)->destroy; [4] } else { saved_destroy = psock->saved_destroy; [5] sock_map_remove_links(sk, psock); rcu_read_unlock(); sk_psock_stop(psock); sk_psock_put(sk, psock); } if (WARN_ON_ONCE(saved_destroy == sock_map_destroy)) return; if (saved_destroy) saved_destroy(sk); } Fix this issue in 3 steps: 1. Prefer 'sk_psock()' over 'sk_psock_get()' at [3]. Since zero refcount is ignored, 'psock' is non-NULL until [2] is completed. 2. Add read lock around [5], to make sure that [1] is not in progress when the former is executed. 3. Since 'sk_psock()' does not adjust reference counting, drop 'sk_psock_put()' and redundant 'sk_psock_stop()' (which is executed by 'sk_psock_drop()' anyway). Fixes: 5b4a79ba65a1 ("bpf, sockmap: Don't let sock_map_{close,destroy,unhash} call itself") Reported-by: syzbot+f363afac6b0ace576f45@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f363afac6b0ace576f45 Signed-off-by: Dmitry Antipov --- net/core/sock_map.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index d3dbb92153f2..1eeb1d3a6b71 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -1649,16 +1649,16 @@ void sock_map_destroy(struct sock *sk) struct sk_psock *psock; rcu_read_lock(); - psock = sk_psock_get(sk); + psock = sk_psock(sk); if (unlikely(!psock)) { rcu_read_unlock(); saved_destroy = READ_ONCE(sk->sk_prot)->destroy; } else { + read_lock_bh(&sk->sk_callback_lock); saved_destroy = psock->saved_destroy; + read_unlock_bh(&sk->sk_callback_lock); sock_map_remove_links(sk, psock); rcu_read_unlock(); - sk_psock_stop(psock); - sk_psock_put(sk, psock); } if (WARN_ON_ONCE(saved_destroy == sock_map_destroy)) return; -- 2.46.0