From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 7C5493242BD; Fri, 4 Sep 2026 05:51:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788501097; cv=none; b=Cmr6iBLIzMo8fhj1NKMoY13U9t71+PWRjfb5nrq+NRp6W897xEGVsUD4hzAKl3vsVxe3LBvUvEU1VQKyYchKr4GAWkDT7kbS5NGTF6CRTk6Hnheovt20LCxx/oeU6Q26ptsAycxZaQiRNbCdrLH24mZXuFgN6oUKEfPKpY4xERI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788501097; c=relaxed/simple; bh=3I8+Xl77QUCGs/77AjwxWRE5ALcKvEHxE64ebkYGFMg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EJBVpSxIRuKr2XQbJWHcTjKt2BBYhjJRYG8cL7QkaFY2BpmflOWHuhNWcW2w1nejILiOXPzNgJy2u3LBbuVMoaKPUyNt2KIkC3PuzZP0js2fY1ZZqpTcvLHGM8B/QCz5ZpKKSiXYj8iMasxQr+CBUZzmrD82zq6tSnYD5E+vWyM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xjN3by6s; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xjN3by6s" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BE9311F00A3D; Fri, 4 Sep 2026 05:51:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788501096; bh=YGzDRHInDdt8/XPQV9GYRWdu+Lb52qn6VoUcsxKCXEY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=xjN3by6s5WQ6i1bsQl+6qMS3yZPfKnWqcoeBfn+8h3iTUmCgibrjbeoYO3ZDez1G/ FK3rEMNFSSSa7Lsa6W3aPcUI8/FE823HzdZYQ27U6f+QPQORDa/sG4cXD2U6VjbkcH +JJ1LZz1S0TlRoQwP+4DK+i9UYyhG/4e3Z2LYA8A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chris Mason , Jeff Layton , Chuck Lever Subject: [PATCH 6.18 288/552] sunrpc: init gssp_lock before publishing proc entry Date: Fri, 4 Sep 2026 06:57:25 +0200 Message-ID: <20260904045756.484232925@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045747.813364717@linuxfoundation.org> References: <20260904045747.813364717@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Mason commit 5ce1ed6159731a41fdd0b03eedbed4e147036a5a upstream. create_use_gss_proxy_proc_entry() publishes /proc/net/rpc/use-gss-proxy via proc_create_data() before init_gssp_clnt() runs mutex_init() on sn->gssp_lock. Once the dentry is linked under proc_subdir_lock it is immediately reachable from userspace, so a write that lands in the window drives set_gssp_clnt() into mutex_lock() on a zero-initialized struct mutex. create_use_gss_proxy_proc_entry(net) proc_create_data("use-gss-proxy", ...) /* dentry live */ init_gssp_clnt(sn) mutex_init(&sn->gssp_lock) /* too late */ write_gssp() set_gssp_clnt(net) mutex_lock(&sn->gssp_lock) /* uninitialized */ gssp_rpc_create(...) sn->gssp_clnt = clnt mutex_unlock(&sn->gssp_lock) The window spans only the two statements between proc_create_data() returning and init_gssp_clnt(), so a writer reaches it only if the registering thread is preempted there while another task is already opening the freshly published file. register_pernet_subsys() runs in preemptible context under pernet_ops_rwsem, so that preemption is possible, and the window widens on auth_rpcgss module load, when the proc entry is created for every live net namespace whose tasks are already running. A writer that wins the race locks a zero-filled struct mutex. On CONFIG_DEBUG_MUTEXES the missing magic value trips a "lock used without init" splat; on a production kernel the fast path acquires the lock via CMPXCHG(owner, 0, current). In the latter case a second writer that arrives before init_gssp_clnt() re-zeroes owner can enter set_gssp_clnt() concurrently, shut down the first writer's clnt while it is still in use, and leak the loser's clnt. Fix by initializing sn->gssp_lock in sunrpc_init_net() so its lifetime matches the sunrpc_net it lives in. sn->gssp_clnt is already NULL from the kzalloc that backs net_generic storage, so the lazy helper is no longer needed; drop init_gssp_clnt(), its prototype, and the call from create_use_gss_proxy_proc_entry(). sunrpc.ko is a build-time dependency of auth_rpcgss.ko, so sunrpc_init_net() has always run on every netns before any auth_gss pernet init can publish the proc entry. Fixes: 030d794bf498 ("SUNRPC: Use gssproxy upcall for server RPCGSS authentication.") Cc: stable@vger.kernel.org Assisted-by: kres:claude-opus-4-7 Signed-off-by: Chris Mason Reviewed-by: Jeff Layton Link: https://patch.msgid.link/20260530-tier2-local-v2-1-5a0fd532db57@oracle.com Signed-off-by: Chuck Lever Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/auth_gss/gss_rpc_upcall.c | 6 ------ net/sunrpc/auth_gss/gss_rpc_upcall.h | 1 - net/sunrpc/auth_gss/svcauth_gss.c | 1 - net/sunrpc/sunrpc_syms.c | 1 + 4 files changed, 1 insertion(+), 8 deletions(-) --- a/net/sunrpc/auth_gss/gss_rpc_upcall.c +++ b/net/sunrpc/auth_gss/gss_rpc_upcall.c @@ -121,12 +121,6 @@ out: return result; } -void init_gssp_clnt(struct sunrpc_net *sn) -{ - mutex_init(&sn->gssp_lock); - sn->gssp_clnt = NULL; -} - int set_gssp_clnt(struct net *net) { struct sunrpc_net *sn = net_generic(net, sunrpc_net_id); --- a/net/sunrpc/auth_gss/gss_rpc_upcall.h +++ b/net/sunrpc/auth_gss/gss_rpc_upcall.h @@ -29,7 +29,6 @@ int gssp_accept_sec_context_upcall(struc struct gssp_upcall_data *data); void gssp_free_upcall_data(struct gssp_upcall_data *data); -void init_gssp_clnt(struct sunrpc_net *); int set_gssp_clnt(struct net *); void clear_gssp_clnt(struct sunrpc_net *); --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -1468,7 +1468,6 @@ static int create_use_gss_proxy_proc_ent &use_gss_proxy_proc_ops, net); if (!*p) return -ENOMEM; - init_gssp_clnt(sn); return 0; } --- a/net/sunrpc/sunrpc_syms.c +++ b/net/sunrpc/sunrpc_syms.c @@ -54,6 +54,7 @@ static __net_init int sunrpc_init_net(st INIT_LIST_HEAD(&sn->all_clients); spin_lock_init(&sn->rpc_client_lock); spin_lock_init(&sn->rpcb_clnt_lock); + mutex_init(&sn->gssp_lock); return 0; err_pipefs: