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 6DB82231836 for ; Sat, 5 Sep 2026 15:46:13 +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=1788623174; cv=none; b=MsCv3nG62FgNjrs7nyX34PXBF20bSpBMkvvam17T2lxV6VzuJKjBxghBPeQn6F9u8B1TbeQfwsMhaxa0txu1zEmjvxvrmlXzNZ6kUfUaf0lPLiWnb8pc2ImQf4oBkdXtzPUXPeAlZS7Aoqp0JuS8IlaM4ljYfCEOofwu11+lzAQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788623174; c=relaxed/simple; bh=bVZixwz5QuzV6BSsFmbl3cmmSJFndNddwNuoL+fEiso=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lpRXbYbqKsC30A8N8fIG/FWtC+ClQXOlxNc1tXSHx7Yw4F+Jnv7g1bN7E9Dj6osfDWk6Yq9tbza7xntJj5mOB88QYndtv82U1eeKVg3mprXrYj04WuYKLEMivlPJxsQsO+LEIqvq0r3daZ14k3kBDXyNtIjx8wLmkhAFL5nkFiA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZeMNC2X6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZeMNC2X6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 758D21F00A3A; Sat, 5 Sep 2026 15:46:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788623173; bh=lW33tpZl+NmhO/Xl7nAg60ex0t8xN0HaoRzkf7WkqOc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZeMNC2X6UZQkrWanFzbMx+ssla7AWMdzb8fMJyDjdNvjaANO5BjtdL2aF9h8uu6QD UfqQ/qSpcw9lLZl5eUoFDirjY0jSf2c5evkWwKLlHwoocvNhOSYnWbdTSKvm0w5miW r4O2PQ8SjBSUQamrlt4Rb5ahfiuoPb3t6mpIz1UT2It+i9lKh3G1lcGYPd/6IV+Z43 uPn/aYVrBEwST1n0qH2w0o40g945bYIplhFx365uU8AfRpv/R05+GT7xJf9cR0xiYA 8ueccR9gNSwLAoWLbuTrVx47UhFwTGYUoNFWXgbRzNL2UogZhqpbjxTI6WIjptTrre AzCkkLGJKcgMQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Jeff Layton , Chuck Lever , Sasha Levin Subject: [PATCH 6.6.y] nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net Date: Sat, 5 Sep 2026 11:46:10 -0400 Message-ID: <20260905154610.395453-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090340-ambition-quench-5a86@gregkh> References: <2026090340-ambition-quench-5a86@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jeff Layton [ Upstream commit bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4 ] 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 [ adapted service-thread disposal state to the existing workqueue implementation by embedding it in struct nfsd_net ] Signed-off-by: Sasha Levin --- fs/nfsd/filecache.c | 70 ++++++++++++--------------------------------- fs/nfsd/netns.h | 4 ++- 2 files changed, 21 insertions(+), 53 deletions(-) diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index 0ff07d53931f2..56983df573279 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -60,12 +60,6 @@ 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 { - struct work_struct work; - spinlock_t lock; - struct list_head freeme; -}; - static struct workqueue_struct *nfsd_filecache_wq __read_mostly; static struct kmem_cache *nfsd_file_slab; @@ -413,16 +407,14 @@ nfsd_file_dispose_list(struct list_head *dispose) 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; - - spin_lock(&l->lock); - list_move_tail(&nf->nf_gc, &l->freeme); - spin_unlock(&l->lock); - queue_work(nfsd_filecache_wq, &l->work); + spin_lock(&nn->fcache_dispose_lock); + list_move_tail(&nf->nf_gc, &nn->fcache_dispose_list); + spin_unlock(&nn->fcache_dispose_lock); + queue_work(nfsd_filecache_wq, &nn->fcache_dispose_work); } } @@ -651,12 +643,12 @@ static void nfsd_file_delayed_close(struct work_struct *work) { LIST_HEAD(head); - struct nfsd_fcache_disposal *l = container_of(work, - struct nfsd_fcache_disposal, work); + struct nfsd_net *nn = container_of(work, struct nfsd_net, + fcache_dispose_work); - spin_lock(&l->lock); - list_splice_init(&l->freeme, &head); - spin_unlock(&l->lock); + spin_lock(&nn->fcache_dispose_lock); + list_splice_init(&nn->fcache_dispose_list, &head); + spin_unlock(&nn->fcache_dispose_lock); nfsd_file_dispose_list(&head); } @@ -825,44 +817,15 @@ __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(sizeof(*l), GFP_KERNEL); - if (!l) - return NULL; - INIT_WORK(&l->work, nfsd_file_delayed_close); - spin_lock_init(&l->lock); - INIT_LIST_HEAD(&l->freeme); - return l; -} - -static void -nfsd_free_fcache_disposal(struct nfsd_fcache_disposal *l) -{ - cancel_work_sync(&l->work); - 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; + INIT_WORK(&nn->fcache_dispose_work, nfsd_file_delayed_close); + spin_lock_init(&nn->fcache_dispose_lock); + INIT_LIST_HEAD(&nn->fcache_dispose_list); + return 0; } /** @@ -881,8 +844,11 @@ 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); + cancel_work_sync(&nn->fcache_dispose_work); + nfsd_file_dispose_list(&nn->fcache_dispose_list); } void diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index 0ecc5527a8f1a..980abc0a22d5c 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -207,7 +207,9 @@ struct nfsd_net { /* utsname taken from the process that starts the server */ char nfsd_name[UNX_MAXNODENAME+1]; - struct nfsd_fcache_disposal *fcache_disposal; + struct work_struct fcache_dispose_work; + spinlock_t fcache_dispose_lock; + struct list_head fcache_dispose_list; siphash_key_t siphash_key; -- 2.53.0