From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793968642; b=ejSqKb4E/ayQNvsK6Nf8tAWTpsh809gv38dwK1uftcTCLU7VvBfa2Uu6mfXAAWn3OpsX GZc6JyI0+qMJloEDK8YCF88OEg/6TjZWbseKVU6VVWoKdPi3fmJlf24EnOMfeJP33o/om SSQ6jcPlIDexAO8gXXaK2wdEcVPPpu6Eg4xQ+CFO4AOqK9hsQuFcX6+7oWrb0JzEJln4R 4LH3y59T5gXG/orWjZn36bT/nr0lfu3HNpd9/2m87kG+h0I8bKZqEnsznN4Z6/eKRsIBK gemJlFu3DZbgyE1rohxIAjrV+1Ekxbf0RIwUiHiqodhT+N/do4XWO2nU3kZXtER7pQQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793968642; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=DEkuHzeqdAOf5ibe6j0Ym28Fkv5pK9E1qx2ZtvrLrXE=; b=rhCPehEckvnKOUKPb7Yzh3ngJTxGiTsOSW9wzrQ9JbNABmzQcy0xHL7k+3RFnM8g9+j8 GBv3DAmDgaukog8FmFu1MPq4lohZC+1Ymzhq+zcoMQvqlSlO5bGW6/cS71cpt9ccZGHCB JNNoreDAxBCqEO+/W6YjiItLWJmFdZPOvFL75o7XjkWNlZm3VxSXS4PAegyUAmET5d/e7 kBImPdBXnn6ue7A3uSazMG29obWcsEiyuzjb1ioSisllD23va703wfxrALxBAANGovR3J 4vz5QSLZ7g0ssrNITt6XvRjYcVkgmGZ3ChkZmSnccf5g+bxENjsW5bXItPjjZZMPkEA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Nz7bnszW; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DB0B5606A32F for ; Fri, 6 Nov 2026 12:37:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Nz7bnszW Received: by smtp.kernel.org (Postfix) with ESMTPSA id 467E31F008A2; Fri, 6 Nov 2026 12:37:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793968641; bh=DEkuHzeqdAOf5ibe6j0Ym28Fkv5pK9E1qx2ZtvrLrXE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Nz7bnszWOjZPsZwGiW4wy2KvkPEFpjHU7RaeAfYdNKy65hWmUsU1E2T29A9BrPNjd VLz5AGhsYHpTcWYgYZpkXHCkKmhb3rgEhfzciylNFE2QtSYMh/JmmaM/ilBd7ydKPW p3Cjd5GAES1BfMDP229MMKOpSvcar4UdXVshaXZYiuQv5PLudc8DwGi8tyjxTe6Y1k 4XbQ2nBBOf+6OTqtxciVX1nox2dmpa36DzZjwTSXvEioU7zUqJn/UBW6UDu/25Ujsv kszsHEbEXb+G32Hkem6D5ubimfEML6bvxF7XJA4WazngskZ/+694VWTH+5RSdDoW0n cSAnklM1iHxaw== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , syzbot+d5c77cabf7a3492aa650@syzkaller.appspotmail.com, Sasha Levin Subject: [PATCH 5.15.y 1/2] NFSD: Move the cld upcall message out of the caller's stack frame Date: Fri, 6 Nov 2026 07:37:19 -0500 Message-ID: <20261106123630.4042374-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110456-hypocrite-villain-ea3d@gregkh> References: <2026110456-hypocrite-villain-ea3d@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chuck Lever [ Upstream commit c559b05610557fa3c6c30259261f6dae523b3f23 ] __cld_pipe_upcall() builds its struct rpc_pipe_msg on the stack and hands it to rpc_queue_upcall(), which links it into a list the pipe owns until the message is released. Only the completion rules keep that frame alive for as long as the pipe refers to it, and the peer that drives those rules is an untrusted userspace daemon. The gss and idmap upcalls do not take that on: each keeps the message in the object it already allocates. Do the same here and put the message in struct cld_upcall, beside the reply buffer it carries. cld_pipe_destroy_msg() then reaches the upcall from the message directly rather than through msg->data. Reported-by: syzbot+d5c77cabf7a3492aa650@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d5c77cabf7a3492aa650 Link: https://patch.msgid.link/20260901-alemi-v2-2-e163f94a3a6e@kernel.org Signed-off-by: Chuck Lever Stable-dep-of: 2a83fcb50f3c ("NFSD: Complete a cld upcall when the daemon closes the pipe") Signed-off-by: Sasha Levin --- fs/nfsd/nfs4recover.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c index e0cb4856ca565..274c6e0aa60f2 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -720,6 +720,7 @@ struct cld_upcall { struct completion cu_done; /* daemon has read the whole upcall; protected by cn_lock */ bool cu_inflight; + struct rpc_pipe_msg cu_pipe_msg; union { struct cld_msg_hdr cu_hdr; struct cld_msg cu_msg; @@ -731,22 +732,22 @@ static int __cld_pipe_upcall(struct rpc_pipe *pipe, void *cmsg, struct nfsd_net *nn) { int ret; - struct rpc_pipe_msg msg; struct cld_upcall *cup = container_of(cmsg, struct cld_upcall, cu_u); + struct rpc_pipe_msg *msg = &cup->cu_pipe_msg; - memset(&msg, 0, sizeof(msg)); - msg.data = cmsg; - msg.len = nn->client_tracking_ops->msglen; + memset(msg, 0, sizeof(*msg)); + msg->data = cmsg; + msg->len = nn->client_tracking_ops->msglen; - ret = rpc_queue_upcall(pipe, &msg); + ret = rpc_queue_upcall(pipe, msg); if (ret < 0) { goto out; } wait_for_completion(&cup->cu_done); - if (msg.errno < 0) - ret = msg.errno; + if (msg->errno < 0) + ret = msg->errno; out: return ret; } @@ -918,9 +919,8 @@ cld_pipe_downcall(struct file *filp, const char __user *src, size_t mlen) static void cld_pipe_destroy_msg(struct rpc_pipe_msg *msg) { - struct cld_msg *cmsg = msg->data; - struct cld_upcall *cup = container_of(cmsg, struct cld_upcall, - cu_u.cu_msg); + struct cld_upcall *cup = container_of(msg, struct cld_upcall, + cu_pipe_msg); struct cld_net *cn = cup->cu_net; /* -- 2.53.0