From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailtransmit05.runbox.com (mailtransmit05.runbox.com [185.226.149.38]) (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 AA72722324 for ; Fri, 17 May 2024 09:32:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.226.149.38 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715938330; cv=none; b=R+JtcqBcwDqMBwXFglI8wwaKYRj7BsfG+8DNh8YoR5KKeNIDbxhn318oupbGHiaanK4/1qgmufgKivdjYf1WaUyHy8vSw4vJjEPr/uMFK/BhTZzicM54GIjv/wGNulTWnJJf+KWNupgH86EahFujPIZkB8jukEoEasMZnY7UwOU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715938330; c=relaxed/simple; bh=kXzSCaoHprIm7lNjKNUMgvG3ZWiIZOpe+OGbnRBrq5E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=k4F905smPLR7UlNqGzHrawjCiSYqJZb0UeA4rpmjLvJWsTb+S5cKx0sGAuNI1s0Y0UfYFTdHOVOub1NTL2k4OhndaZUPb5XRH4+t1gl4tthLOrNvHecvOlMbjoE88FAuKbvBWcrHV7V2iI3wizQs9iTgqMI3uqwsUleBizfwLf8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rbox.co; spf=pass smtp.mailfrom=rbox.co; dkim=pass (2048-bit key) header.d=rbox.co header.i=@rbox.co header.b=Dwvx0H+d; arc=none smtp.client-ip=185.226.149.38 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rbox.co Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rbox.co Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=rbox.co header.i=@rbox.co header.b="Dwvx0H+d" Received: from mailtransmit02.runbox ([10.9.9.162] helo=aibo.runbox.com) by mailtransmit05.runbox.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1s7twa-005L3x-HT; Fri, 17 May 2024 11:32:04 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=rbox.co; s=selector2; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From; bh=yokzBYS17hWADW2KY3nlMvcWNr12nOM5EuszZJW34Xw=; b=Dwvx0H+dAnU1WYspSfgAi9j/kw bcWbACXXEIWvdEaPnjzzIEA84Thty2gZQ5c8ktXZV7GU5ESHOxaYelyQOEJZTzPOxS2x9Ra/yOxpD ipCp4vnQDP3H5gZZPRQh035m+K5gY3Q1kjM96kakA8I+L4qpwWmKb7Q5RnwAVb6WhrJ5Oxn1CAVep eqmhMwEp0CnOEi49rs8vy8zEXPqYFJuX+8i69F29uM7jxTSfyTjSJD2eDt7XmstXPloc6QzX2aNqx ahnwtkXKN8RZMgtNeGaaIAj9WwSWsXlB5LmO172OWxjUcb0xAh+gTmXjQL5/6R3zU1ZdCPE+l5qbQ GVIeI/RQ==; Received: from [10.9.9.74] (helo=submission03.runbox) by mailtransmit02.runbox with esmtp (Exim 4.86_2) (envelope-from ) id 1s7twV-0000b4-5E; Fri, 17 May 2024 11:31:59 +0200 Received: by submission03.runbox with esmtpsa [Authenticated ID (604044)] (TLS1.2:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.93) id 1s7twQ-0042Jz-2t; Fri, 17 May 2024 11:31:54 +0200 From: Michal Luczaj To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, kuniyu@amazon.com, shuah@kernel.org, Michal Luczaj Subject: [PATCH v3 net 1/2] af_unix: Fix garbage collection of embryos carrying OOB with SCM_RIGHTS Date: Fri, 17 May 2024 11:27:01 +0200 Message-ID: <20240517093138.1436323-2-mhal@rbox.co> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240517093138.1436323-1-mhal@rbox.co> References: <20240517093138.1436323-1-mhal@rbox.co> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit GC attempts to explicitly drop oob_skb's reference before purging the hit list. The problem is with embryos: kfree_skb(u->oob_skb) is never called on an embryo socket. The python script below [0] sends a listener's fd to its embryo as OOB data. While GC does collect the embryo's queue, it fails to drop the OOB skb's refcount. The skb which was in embryo's receive queue stays as unix_sk(sk)->oob_skb and keeps the listener's refcount [1]. Tell GC to dispose embryo's oob_skb. [0]: from array import array from socket import * addr = '\x00unix-oob' lis = socket(AF_UNIX, SOCK_STREAM) lis.bind(addr) lis.listen(1) s = socket(AF_UNIX, SOCK_STREAM) s.connect(addr) scm = (SOL_SOCKET, SCM_RIGHTS, array('i', [lis.fileno()])) s.sendmsg([b'x'], [scm], MSG_OOB) lis.close() [1] $ grep unix-oob /proc/net/unix $ ./unix-oob.py $ grep unix-oob /proc/net/unix 0000000000000000: 00000002 00000000 00000000 0001 02 0 @unix-oob 0000000000000000: 00000002 00000000 00010000 0001 01 6072 @unix-oob Fixes: 4090fa373f0e ("af_unix: Replace garbage collection algorithm.") Signed-off-by: Michal Luczaj Reviewed-by: Kuniyuki Iwashima --- net/unix/garbage.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/net/unix/garbage.c b/net/unix/garbage.c index 1f8b8cdfcdc8..dfe94a90ece4 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -342,6 +342,18 @@ enum unix_recv_queue_lock_class { U_RECVQ_LOCK_EMBRYO, }; +static void unix_collect_queue(struct unix_sock *u, struct sk_buff_head *hitlist) +{ + skb_queue_splice_init(&u->sk.sk_receive_queue, hitlist); + +#if IS_ENABLED(CONFIG_AF_UNIX_OOB) + if (u->oob_skb) { + WARN_ON_ONCE(skb_unref(u->oob_skb)); + u->oob_skb = NULL; + } +#endif +} + static void unix_collect_skb(struct list_head *scc, struct sk_buff_head *hitlist) { struct unix_vertex *vertex; @@ -365,18 +377,11 @@ static void unix_collect_skb(struct list_head *scc, struct sk_buff_head *hitlist /* listener -> embryo order, the inversion never happens. */ spin_lock_nested(&embryo_queue->lock, U_RECVQ_LOCK_EMBRYO); - skb_queue_splice_init(embryo_queue, hitlist); + unix_collect_queue(unix_sk(skb->sk), hitlist); spin_unlock(&embryo_queue->lock); } } else { - skb_queue_splice_init(queue, hitlist); - -#if IS_ENABLED(CONFIG_AF_UNIX_OOB) - if (u->oob_skb) { - kfree_skb(u->oob_skb); - u->oob_skb = NULL; - } -#endif + unix_collect_queue(u, hitlist); } spin_unlock(&queue->lock); -- 2.45.0