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=1793933968; b=V94zc5brbhjH2WrlTLjTlLy1UDy3OqkrMYjZgewjC1xGHbiuMHrQBnP6ntsBRqtW15Jf PRKDBgowHksy/Rijp8nvip316rj8Z7ctIGaix8R4Gq1t9izRvpqrNuI3912ZOeRZ0HHj1 3xjmjq1xZyyCuvHwp2MAq9qHMtHZl9pMPlLHjOIN/8D33gEADFPmbMVWoijahz2LfsAUT x8oFwqWyxihyAQshgyjccgPO+MN9zX8SSzVYK4xoNIx634WPFuhX/hOQLXn2E9uwzMO7h OxLdYylaRFoH57MPBT0sX6WCN+vxPPAvP2VaUhqMTEXwnSIwojM62uvgO1DgAuSqE5A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793933968; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=2xM7ilbUrVl91JV0+ZiZ+00pPVP9keJyhUy+Qn21GNs=; b=xYHAohxcnkcikiwkqXI/TSf1qQ2q5sAmgvbYOLQjloYbySnQUf/X81ThkfVG+2OHLaC+ G1M8U/q+rYCzyPPkifxnJErNBHEHQw8d3a+L4hq62pU+5EGFSJXA05FTiBX0TtmTKOzq/ iFQKYsUSuJqpn65DTinEZQZZ3GQs7U3oAsdV31NdkaariXuOTygw8JdA0tXqJGd6jz3E9 jGFYy7TaydaIovYQjEOyheythss0E8GErtuM/0if2GWe6ir7ecC+pjqmuj4VeaMffHJ5L G89emN7pqUg6MmiJqrOi4YsNlFaUo7bncGRmyzBfaF4A7HWlVyOnvH4o14/5OJHiBIw== 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=a+0kVpFV; 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 7A743606A31B for ; Fri, 6 Nov 2026 02:59:28 +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=a+0kVpFV Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C5D21F008A2; Fri, 6 Nov 2026 02:59:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793933968; bh=2xM7ilbUrVl91JV0+ZiZ+00pPVP9keJyhUy+Qn21GNs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=a+0kVpFVTThHzfxh9JAwBpxuSUNfJR465X4XFGAaBRvw4dmqtdAT14gmqt8X/tbhs zn4RltPF9wmwMk95qZ9LV4gx/KyIkMAanE6cdcau9yPn3XtywSB028K9SsLGRbJp1t z+3qLZq7dllf1dr8hGZHSy0MYD9M8rNpFmzPq+F0WCTYZsHyTFbVACm04IcNIlxmzd 6/euArQ1DVIuzghwQKqIYqrRDAdbjDhrd1LvrIXIYVWFd1c1vBYKFPNcN2PQL4M+me zVUJPKMwdd/NR0kZTvbQc9ey1TlntsIVjn7QaJaL+hgK0QUAvye0nR2yXL/vg4MToa zAP55RJKKr8Qw== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , syzbot+d5c77cabf7a3492aa650@syzkaller.appspotmail.com, Sasha Levin Subject: [PATCH 6.12.y 1/2] NFSD: Move the cld upcall message out of the caller's stack frame Date: Thu, 5 Nov 2026 21:59:25 -0500 Message-ID: <20261106025913.3959182-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110453-devotee-unsuited-ab14@gregkh> References: <2026110453-devotee-unsuited-ab14@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 104dafbe881bc..b493bb059a8b0 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -730,6 +730,7 @@ 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; @@ -741,22 +742,22 @@ 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; } @@ -929,9 +930,8 @@ 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