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 5D9D54A8FF9 for ; Thu, 3 Sep 2026 13:46:11 +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=1788443183; cv=none; b=prJiiv9Sl3LqA5KeaKThpUsW1HXO4H6t4jn4MwsxE9EVv8J66n9u+O/Qdwyjf9Liei23h1HiugN7Qv/v+9hf9tUpin6RgmJM0tgHa9OumhA2ubQM7JME7CIpG4KSxwnxyMJYmEP+z3WSu9ZLJbivBUF7bZHkgY/1mkhvKWIUkZU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788443183; c=relaxed/simple; bh=cIrjdxQ2qPPqeKbASzxLpyiJGQHQE10KrjoXWy0YoPY=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=WyCUTSsxu8zWNixRNJY/BYbNnv04dgUjZSKIRJE61odsW38wMTnCJxOiLLP6rqllQfEJ1w/EuWczvlzGsIEonUpA542gWPANKFNipvzc+m7nePf8uTKiiHKFvuQiojO/H/JvJdAdRsFD3MvFhEdpt+VAekn3JcCfwR8MbIJPknI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=kW2Ora4b; 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="kW2Ora4b" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A5AC1F00AC4; Thu, 3 Sep 2026 13:46:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788443168; bh=wdF9l9RbVRdzr546NHIpDo5jsWhFmRrLYZcDSi6/uX4=; h=Subject:To:Cc:From:Date; b=kW2Ora4bS3eTjyleKXnR/f3spMf1DbYGm7Nx8kz+RjirSQQ11s3u1Ej9bclTvtYvQ mbVSeNqkxkr6TckBypQnyBZ6FVk5HPyS1qZPzx+3n3lIaM/NxMhsIrA+xgoZwAONI6 WzPrW1cOsY6wass+m+YixcWHOwhd1lkVtslcabOY= Subject: FAILED: patch "[PATCH] NFSD: Guard admin state-revocation walks with NFSD_NET_UP" failed to apply to 6.12-stable tree To: cel@kernel.org,jlayton@kernel.org,xiaowu.417@qq.com Cc: From: Date: Thu, 03 Sep 2026 15:20:53 +0200 Message-ID: <2026090353-oat-exclude-4fc9@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378 # git commit -s git send-email --to '' --in-reply-to '2026090353-oat-exclude-4fc9@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Sun, 21 Jun 2026 12:25:51 -0400 Subject: [PATCH] NFSD: Guard admin state-revocation walks with NFSD_NET_UP Writing to /proc/fs/nfsd/unlock_filesystem, or sending the NFSD_CMD_UNLOCK_FILESYSTEM or NFSD_CMD_UNLOCK_EXPORT netlink command, walks the NFSv4 client hash tables to revoke open state and cancel async COPY operations. All three handlers gate that walk on nn->nfsd_serv, but a listener added via portlist or netlink listener_set sets nn->nfsd_serv before any nfsd thread starts. nfsd_startup_net() has not yet allocated nn->conf_id_hashtbl, so the walkers dereference a NULL table. A local administrator with CAP_SYS_ADMIN can crash the kernel this way without ever starting the server. nn->nfsd_serv is set when the service is created, which precedes table allocation. NFSD_NET_UP instead brackets the window where the tables are live: set at the end of nfsd_startup_net() and cleared in nfsd_shutdown_net() after they are freed, both under nfsd_mutex. Gating the three unlock paths on NFSD_NET_UP fixes the startup-time NULL dereference while preserving the earlier post-shutdown use-after-free fix. Reported-by: XIAO WU Fixes: 1ac3629bf012 ("nfsd: prepare for supporting admin-revocation of state") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Link: https://patch.msgid.link/20260621162551.2469460-1-cel@kernel.org Signed-off-by: Chuck Lever diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index c413ed0810b9..8351ccaae59c 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1588,10 +1588,9 @@ static bool nfsd4_copy_on_sb(const struct nfsd4_copy *copy, * @net: net namespace containing the copy operations * @sb: targeted superblock * - * Context: Caller must hold nfsd_mutex with nn->nfsd_serv confirmed - * non-NULL. nfs4_state_destroy_net() frees conf_id_hashtbl - * at server shutdown without clearing the pointer, so a - * walk without these guarantees iterates freed slab memory. + * Context: Caller must hold nfsd_mutex with NFSD_NET_UP set. Outside + * that window nn->conf_id_hashtbl is unallocated or freed, + * so the walk would dereference a NULL or dangling pointer. */ void nfsd4_cancel_copy_by_sb(struct net *net, struct super_block *sb) { diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 4ae5d65c056a..a4398dc861a5 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1946,10 +1946,9 @@ static void revoke_one_stid(struct nfsd_net *nn, struct nfs4_client *clp, * The clients which own the states will subsequently be notified that the * states have been "admin-revoked". * - * Context: Caller must hold nfsd_mutex with nn->nfsd_serv confirmed - * non-NULL. nfs4_state_destroy_net() frees conf_id_hashtbl - * at server shutdown without clearing the pointer, so a - * walk without these guarantees iterates freed slab memory. + * Context: Caller must hold nfsd_mutex with NFSD_NET_UP set. Outside + * that window nn->conf_id_hashtbl is unallocated or freed, + * so the walk would dereference a NULL or dangling pointer. */ void nfsd4_revoke_states(struct nfsd_net *nn, struct super_block *sb) { @@ -2024,10 +2023,9 @@ static struct nfs4_stid *find_one_export_stid(struct nfs4_client *clp, * Userspace (exportfs -u) sends this after removing the last client * for a path, enabling the underlying filesystem to be unmounted. * - * Context: Caller must hold nfsd_mutex with nn->nfsd_serv confirmed - * non-NULL. nfs4_state_destroy_net() frees conf_id_hashtbl - * at server shutdown without clearing the pointer, so a - * walk without these guarantees iterates freed slab memory. + * Context: Caller must hold nfsd_mutex with NFSD_NET_UP set. Outside + * that window nn->conf_id_hashtbl is unallocated or freed, + * so the walk would dereference a NULL or dangling pointer. */ void nfsd4_revoke_export_states(struct nfsd_net *nn, const struct path *path) { diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index caf59421f8f4..bc16fc7ca24f 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -299,7 +299,7 @@ static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size) error = nlmsvc_unlock_all_by_sb(path.dentry->d_sb); mutex_lock(&nfsd_mutex); nn = net_generic(netns(file), nfsd_net_id); - if (nn->nfsd_serv) { + if (test_bit(NFSD_NET_UP, &nn->flags)) { nfsd4_cancel_copy_by_sb(netns(file), path.dentry->d_sb); nfsd4_revoke_states(nn, path.dentry->d_sb); } else { @@ -2424,7 +2424,7 @@ int nfsd_nl_unlock_filesystem_doit(struct sk_buff *skb, error = nlmsvc_unlock_all_by_sb(path.dentry->d_sb); mutex_lock(&nfsd_mutex); - if (nn->nfsd_serv) { + if (test_bit(NFSD_NET_UP, &nn->flags)) { nfsd4_cancel_copy_by_sb(net, path.dentry->d_sb); nfsd4_revoke_states(nn, path.dentry->d_sb); } else { @@ -2471,7 +2471,7 @@ int nfsd_nl_unlock_export_doit(struct sk_buff *skb, struct genl_info *info) return error; mutex_lock(&nfsd_mutex); - if (nn->nfsd_serv) { + if (test_bit(NFSD_NET_UP, &nn->flags)) { nfsd_file_close_export(net, &path); nfsd4_revoke_export_states(nn, &path); } else