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 B4CA74A840A for ; Thu, 3 Sep 2026 13:40:06 +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=1788442822; cv=none; b=Cj75TlxEnx63gQTMejQggenk2KuHQmuDybTdU4FM5WWSS/FkPJ3K6BAYs/bWPFtyxyBEwAR1sZBl60VhDZH6to9FyswDEZYFqWyGTBv56wqo2FvBRDto7U0O0t9qn85y8QOOjmGDXwG+r21HlMkSg8EApn3vKh/Q73sIRI6Nl10= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788442822; c=relaxed/simple; bh=OHsN740BXaQNY2gIe31nJuyAwh8PHmSpwl/aVuC6/G0=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=rlu3OlsqI1kXm9bIMSU9rimGp793hzBT1a9DQMRnad9obdOIrjf62YaLNkEYkjHIXRsLQr/finlnpBLb114Wb4Rd5AnI/XMK32dKD5PA3bxCC65mlqiF0UFxcNYw+OSlqQRHfkS8UyqM4r3hoZoHjAXZbOB+rMDz09/GDYaW1qg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Em4qaTUk; 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="Em4qaTUk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2E5411F00A3E; Thu, 3 Sep 2026 13:40:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788442802; bh=DmVtPG5S1eHhUpHoyq/+qC8hFYNxFttaFRyyUMr3tv4=; h=Subject:To:Cc:From:Date; b=Em4qaTUkhmmAz2zrgPI1psb9ruvWmjLYh+GN9Q+1WhdYSsSsynK6Rrp+T125GSwkA ylYZ7pA/4MO3gxlHV9SUg1GEzhYC4xFBl/SfL0AZq9tVO+bST/xZCVK8flWSYYeswI QidqTwlW+759E0wMotjtu9CRZMx4WBbBxKPUMCNI= Subject: FAILED: patch "[PATCH] nfsd: fix fcache_disposal UAF by inlining dispose state into" failed to apply to 6.18-stable tree To: jlayton@kernel.org,chuck.lever@oracle.com Cc: From: Date: Thu, 03 Sep 2026 15:13:39 +0200 Message-ID: <2026090339-happiest-badass-03c3@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 6.18-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-6.18.y git checkout FETCH_HEAD git cherry-pick -x bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4 # git commit -s git send-email --to '' --in-reply-to '2026090339-happiest-badass-03c3@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Tue, 2 Jun 2026 12:23:19 -0400 Subject: [PATCH] nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net nfsd_file_dispose_list_delayed() defers fput() to nfsd service threads via a per-net freeme queue, preventing the shrinker and GC worker from bearing the cost of closing files (see ffb402596147). However, the queue lives in a separately-allocated struct nfsd_fcache_disposal that is freed by nfsd_free_fcache_disposal_net() during per-net teardown. The global shrinker, laundrette, and fsnotify callbacks can still be inside nfsd_file_dispose_list_delayed() dereferencing that pointer, causing a use-after-free. Inline the spinlock and freeme list directly into struct nfsd_net (as fcache_dispose_lock and fcache_dispose_list), eliminating the separately allocated struct nfsd_fcache_disposal entirely. These fields now have the same lifetime as the net namespace itself, so there is no dangling pointer to chase. nfsd_file_cache_start_net() now just initializes the inline fields and cannot fail due to allocation. nfsd_file_cache_shutdown_net() drains the inline list directly instead of freeing a separate struct. The alloc/free helpers are removed. Fixes: 1463b38e7cf3 ("NFSD: simplify per-net file cache management") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260602-nfsd-testing-v2-7-e4ea62e3cd5c@kernel.org Signed-off-by: Chuck Lever diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index 19beb4d482be..da5a44c31acb 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -62,11 +62,6 @@ static DEFINE_PER_CPU(unsigned long, nfsd_file_releases); static DEFINE_PER_CPU(unsigned long, nfsd_file_total_age); static DEFINE_PER_CPU(unsigned long, nfsd_file_evictions); -struct nfsd_fcache_disposal { - spinlock_t lock; - struct list_head freeme; -}; - static struct kmem_cache *nfsd_file_slab; static struct kmem_cache *nfsd_file_mark_slab; static struct list_lru nfsd_file_lru; @@ -422,25 +417,25 @@ nfsd_file_dispose_list(struct list_head *dispose) } /** - * nfsd_file_dispose_list_delayed - move list of dead files to net's freeme list + * nfsd_file_dispose_list_delayed - queue dead files for nfsd thread disposal * @dispose: list of nfsd_files to be disposed * - * Transfers each file to the "freeme" list for its nfsd_net, to eventually - * be disposed of by the per-net garbage collector. + * Transfers each file to the dispose list in its nfsd_net and wakes an nfsd + * thread to do the actual close. This keeps the cost of fput() in the nfsd + * threads rather than in the shrinker or GC worker. */ static void nfsd_file_dispose_list_delayed(struct list_head *dispose) { - while(!list_empty(dispose)) { + while (!list_empty(dispose)) { struct nfsd_file *nf = list_first_entry(dispose, struct nfsd_file, nf_gc); struct nfsd_net *nn = net_generic(nf->nf_net, nfsd_net_id); - struct nfsd_fcache_disposal *l = nn->fcache_disposal; struct svc_serv *serv; - spin_lock(&l->lock); - list_move_tail(&nf->nf_gc, &l->freeme); - spin_unlock(&l->lock); + spin_lock(&nn->fcache_dispose_lock); + list_move_tail(&nf->nf_gc, &nn->fcache_dispose_list); + spin_unlock(&nn->fcache_dispose_lock); /* * The filecache laundrette is shut down after the @@ -464,17 +459,15 @@ nfsd_file_dispose_list_delayed(struct list_head *dispose) */ void nfsd_file_net_dispose(struct nfsd_net *nn) { - struct nfsd_fcache_disposal *l = nn->fcache_disposal; - - if (!list_empty(&l->freeme)) { + if (!list_empty(&nn->fcache_dispose_list)) { LIST_HEAD(dispose); int i; - spin_lock(&l->lock); - for (i = 0; i < 8 && !list_empty(&l->freeme); i++) - list_move(l->freeme.next, &dispose); - spin_unlock(&l->lock); - if (!list_empty(&l->freeme)) { + spin_lock(&nn->fcache_dispose_lock); + for (i = 0; i < 8 && !list_empty(&nn->fcache_dispose_list); i++) + list_move(nn->fcache_dispose_list.next, &dispose); + spin_unlock(&nn->fcache_dispose_lock); + if (!list_empty(&nn->fcache_dispose_list)) { /* * Wake up another thread to share the work * *before* doing any actual disposing. @@ -698,11 +691,11 @@ nfsd_file_queue_for_close(struct inode *inode, struct list_head *dispose) } /** - * nfsd_file_close_inode - attempt a delayed close of a nfsd_file + * nfsd_file_close_inode - attempt a deferred close of a nfsd_file * @inode: inode of the file to attempt to remove * * Close out any open nfsd_files that can be reaped for @inode. The - * actual freeing is deferred to the dispose_list_delayed infrastructure. + * actual freeing is deferred to the nfsd service threads. * * This is used by the fsnotify callbacks and setlease notifier. */ @@ -952,42 +945,14 @@ __nfsd_file_cache_purge(struct net *net) nfsd_file_dispose_list(&dispose); } -static struct nfsd_fcache_disposal * -nfsd_alloc_fcache_disposal(void) -{ - struct nfsd_fcache_disposal *l; - - l = kmalloc_obj(*l); - if (!l) - return NULL; - spin_lock_init(&l->lock); - INIT_LIST_HEAD(&l->freeme); - return l; -} - -static void -nfsd_free_fcache_disposal(struct nfsd_fcache_disposal *l) -{ - nfsd_file_dispose_list(&l->freeme); - kfree(l); -} - -static void -nfsd_free_fcache_disposal_net(struct net *net) -{ - struct nfsd_net *nn = net_generic(net, nfsd_net_id); - struct nfsd_fcache_disposal *l = nn->fcache_disposal; - - nfsd_free_fcache_disposal(l); -} - int nfsd_file_cache_start_net(struct net *net) { struct nfsd_net *nn = net_generic(net, nfsd_net_id); - nn->fcache_disposal = nfsd_alloc_fcache_disposal(); - return nn->fcache_disposal ? 0 : -ENOMEM; + spin_lock_init(&nn->fcache_dispose_lock); + INIT_LIST_HEAD(&nn->fcache_dispose_list); + return 0; } /** @@ -1006,8 +971,10 @@ nfsd_file_cache_purge(struct net *net) void nfsd_file_cache_shutdown_net(struct net *net) { + struct nfsd_net *nn = net_generic(net, nfsd_net_id); + nfsd_file_cache_purge(net); - nfsd_free_fcache_disposal_net(net); + nfsd_file_dispose_list(&nn->fcache_dispose_list); } void diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index f6b8b340bf8e..5c33c96da28e 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -216,7 +216,8 @@ struct nfsd_net { /* utsname taken from the process that starts the server */ char nfsd_name[UNX_MAXNODENAME+1]; - struct nfsd_fcache_disposal *fcache_disposal; + spinlock_t fcache_dispose_lock; + struct list_head fcache_dispose_list; siphash_key_t siphash_key;