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=1793932852; b=fyBvivtQ9p597RLRLOmdmAx0+QEU6owzqcJAejROx3TVgW1ay4NjzUDE4VohIXucJ54M 0TqpCUqnUuNGBrQLXl5gIPCCzssX0rujFYk27wqude4wKtyT1Aro/fXrt8YtWKcsH21bY G1n0u5IsoH4lsQLCNPOvYQ0bzdZnyuKxBx4UxhrramG90EBpuCVhBdCJZgcM6HIp7pqBn 1okHgZpHKHrGWddTzxDEodX5nm1sEdC2R7lqyrpgSFgWV6DgXK0jyAfkyZfkWIoztZkaE AjrDWm7f77OJteh5RDUqPV2lrZEmWDiCtatxJsgFJY5STm55bGQb8vv4YwMvhbx5aAg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793932852; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=hVqFXu/XEMzvTBG/91kWJiYmOzNs4PawsTsnxwvB+zU=; b=hDEqdyNEB4VjqTybDFXKtT748LbL5+mg6zlFjDyPuAxkfYaP5d6Hki9VaI9VtXNHpi+X Pj2lVwKdFqisRsmAXu4v0yk0JckFzxEsow1tHLuJoKiOpObbR25KjSTbNLJYTFcFIbZVa eoh5XMXrZt4nddSnQayCfHuhcCEM8NZJ4xVBBjKXE9ltYsi25PbofJTVcOVIWiSLibBkL MhZUJINEbp9GpFQ2VkAn864bVsh8WwmEyy4gx8W8F4HTy/3+f670Qktfo1+N/uZh7lk31 Nyx+NjtNDvXjcVmkqFPaihlburxlCHF+wfvFenIqXSavDDlP6+ZOoZVpWGlP1N2cu3A== 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=K7ByaxGU; 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 A0E2F606A326 for ; Fri, 6 Nov 2026 02:40:52 +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=K7ByaxGU Received: by smtp.kernel.org (Postfix) with ESMTPSA id C61491F008A1; Fri, 6 Nov 2026 02:40:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793932852; bh=hVqFXu/XEMzvTBG/91kWJiYmOzNs4PawsTsnxwvB+zU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=K7ByaxGU9VsFu6a3iageNUnwARaX3mVZCiJMHjbBWRMCJ5UP5XNoKjJrQwehznz1A p/ZJHbB/xxqqcEqXsbS58NxN6CaLZt0cTZUldFzfc3wxy3r2X+r0sqjGY716MscKhB lVfD+p6s12np75yzEZNpJKU+/2BZagBS4UExgZvaGfV/FGngtYNs5HowrZxmp6dMxq 2uNpKyP8XWhbhVtopF/26Bbxg1GgSmGSdYt5B2RV7TrgowBtcYxCUYJNZ67jWVgAXE LYx4reVt2uOiSd/Lx69gJAZBJV9Kr3fW9RxVchPEZZVVsT2Sc3sdGBcH7qk2iuUSHj RTfIHKqnHEXUw== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , syzbot+d5c77cabf7a3492aa650@syzkaller.appspotmail.com, Sasha Levin Subject: [PATCH 6.18.y 1/2] NFSD: Move the cld upcall message out of the caller's stack frame Date: Thu, 5 Nov 2026 21:40:49 -0500 Message-ID: <20261106024045.3935499-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110453-musket-ludicrous-f264@gregkh> References: <2026110453-musket-ludicrous-f264@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 d04a7d3aabbc8..b001d3277b9f9 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -711,6 +711,7 @@ 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; @@ -722,22 +723,22 @@ 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; } @@ -910,9 +911,8 @@ 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