From patchwork Wed Aug 21 14:55:32 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13771720 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 729761B1D66; Wed, 21 Aug 2024 14:56:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724252172; cv=none; b=BIB5WgJYbvwZuYT1GyYPzT/ZKAaRCHaGp7coeA8prljUM4XvVQYsFesLmMEnc6ld8Cj5rc/w3baMVqtALnq4hCuzBKdingLosr0U53PiO4dKre7ayFOZNpbmVROIkhyrsjHHcn6tJTFxFsv1JKMYXJMPGyjtWqhhDcAOK57gqOw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724252172; c=relaxed/simple; bh=Mv9C89UEb6BwNWw2CptmrYpVgSGlhxdwnhHXXdBY01o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cX5mgKloKkNJn8e+ZAQL3g5NKYN74KYnebc+nRfOMN78Kjs/YvbKydaJet8bZJMsrd7wnmdJRHaC2YFZlVBwgRVV6EeJEn49FtQT3N6Q6mzJ83XZIcP8BDJqAf40fIVi27vW9d/+8k5dzKHv9+NdQ3BPkIKwDPp/UoO562Rg1o0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=INi9lgfZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="INi9lgfZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B344C32781; Wed, 21 Aug 2024 14:56:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724252172; bh=Mv9C89UEb6BwNWw2CptmrYpVgSGlhxdwnhHXXdBY01o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=INi9lgfZGbfaD5W7ug4tqpRJ2/YIFP0r8Guuu5babDWcnJYGW9d0aElHep7XL+5oA pUtGb4NjFtVxCV+uASDlaeeq38N3tk0NWTXregpIwD064VxhVL4DEImOaw1Kvu5tpn XqAfH1bPw4azR7G5y9b61Rw31koZ38rcPRl1tIcXMagKGZ4KpwJ1W9SPyHVeNRhdxL 4iY/VutZgdejkock0tqROJ3gGziG3KGMxmXRFU1HnCESTcmVYeLPfFc7ztiBXRFJPf n26oLm7U5jOfzuquELPLUUPGcXWbwbaa7rkEBW6cKROrnrE6/QikrR18pXgWDHIXr+ iyPe5+aF5p5/w== From: cel@kernel.org To: Cc: , pvorel@suse.cz, sherry.yang@oracle.com, calum.mackay@oracle.com, kernel-team@fb.com, Jeff Layton , Eirik Fuller Subject: [PATCH 5.15.y 02/18] nfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net Date: Wed, 21 Aug 2024 10:55:32 -0400 Message-ID: <20240821145548.25700-3-cel@kernel.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240821145548.25700-1-cel@kernel.org> References: <20240821145548.25700-1-cel@kernel.org> Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Jeff Layton [ Upstream commit ed9ab7346e908496816cffdecd46932035f66e2e ] Commit f5f9d4a314da ("nfsd: move reply cache initialization into nfsd startup") moved the initialization of the reply cache into nfsd startup, but didn't account for the stats counters, which can be accessed before nfsd is ever started. The result can be a NULL pointer dereference when someone accesses /proc/fs/nfsd/reply_cache_stats while nfsd is still shut down. This is a regression and a user-triggerable oops in the right situation: - non-x86_64 arch - /proc/fs/nfsd is mounted in the namespace - nfsd is not started in the namespace - unprivileged user calls "cat /proc/fs/nfsd/reply_cache_stats" Although this is easy to trigger on some arches (like aarch64), on x86_64, calling this_cpu_ptr(NULL) evidently returns a pointer to the fixed_percpu_data. That struct looks just enough like a newly initialized percpu var to allow nfsd_reply_cache_stats_show to access it without Oopsing. Move the initialization of the per-net+per-cpu reply-cache counters back into nfsd_init_net, while leaving the rest of the reply cache allocations to be done at nfsd startup time. Kudos to Eirik who did most of the legwork to track this down. Cc: stable@vger.kernel.org # v6.3+ Fixes: f5f9d4a314da ("nfsd: move reply cache initialization into nfsd startup") Reported-and-tested-by: Eirik Fuller Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2215429 Signed-off-by: Jeff Layton Stable-dep-of: 4b14885411f7 ("nfsd: make all of the nfsd stats per-network namespace") Signed-off-by: Chuck Lever --- fs/nfsd/cache.h | 2 ++ fs/nfsd/nfscache.c | 25 ++++++++++++++----------- fs/nfsd/nfsctl.c | 10 +++++++++- 3 files changed, 25 insertions(+), 12 deletions(-) diff --git a/fs/nfsd/cache.h b/fs/nfsd/cache.h index f21259ead64b..4c9b87850ab1 100644 --- a/fs/nfsd/cache.h +++ b/fs/nfsd/cache.h @@ -80,6 +80,8 @@ enum { int nfsd_drc_slab_create(void); void nfsd_drc_slab_free(void); +int nfsd_net_reply_cache_init(struct nfsd_net *nn); +void nfsd_net_reply_cache_destroy(struct nfsd_net *nn); int nfsd_reply_cache_init(struct nfsd_net *); void nfsd_reply_cache_shutdown(struct nfsd_net *); int nfsd_cache_lookup(struct svc_rqst *); diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index 2b5417e06d80..587ff31deb6e 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -148,12 +148,23 @@ void nfsd_drc_slab_free(void) kmem_cache_destroy(drc_slab); } -static int nfsd_reply_cache_stats_init(struct nfsd_net *nn) +/** + * nfsd_net_reply_cache_init - per net namespace reply cache set-up + * @nn: nfsd_net being initialized + * + * Returns zero on succes; otherwise a negative errno is returned. + */ +int nfsd_net_reply_cache_init(struct nfsd_net *nn) { return nfsd_percpu_counters_init(nn->counter, NFSD_NET_COUNTERS_NUM); } -static void nfsd_reply_cache_stats_destroy(struct nfsd_net *nn) +/** + * nfsd_net_reply_cache_destroy - per net namespace reply cache tear-down + * @nn: nfsd_net being freed + * + */ +void nfsd_net_reply_cache_destroy(struct nfsd_net *nn) { nfsd_percpu_counters_destroy(nn->counter, NFSD_NET_COUNTERS_NUM); } @@ -169,16 +180,12 @@ int nfsd_reply_cache_init(struct nfsd_net *nn) hashsize = nfsd_hashsize(nn->max_drc_entries); nn->maskbits = ilog2(hashsize); - status = nfsd_reply_cache_stats_init(nn); - if (status) - goto out_nomem; - nn->nfsd_reply_cache_shrinker.scan_objects = nfsd_reply_cache_scan; nn->nfsd_reply_cache_shrinker.count_objects = nfsd_reply_cache_count; nn->nfsd_reply_cache_shrinker.seeks = 1; status = register_shrinker(&nn->nfsd_reply_cache_shrinker); if (status) - goto out_stats_destroy; + return status; nn->drc_hashtbl = kvzalloc(array_size(hashsize, sizeof(*nn->drc_hashtbl)), GFP_KERNEL); @@ -194,9 +201,6 @@ int nfsd_reply_cache_init(struct nfsd_net *nn) return 0; out_shrinker: unregister_shrinker(&nn->nfsd_reply_cache_shrinker); -out_stats_destroy: - nfsd_reply_cache_stats_destroy(nn); -out_nomem: printk(KERN_ERR "nfsd: failed to allocate reply cache\n"); return -ENOMEM; } @@ -216,7 +220,6 @@ void nfsd_reply_cache_shutdown(struct nfsd_net *nn) rp, nn); } } - nfsd_reply_cache_stats_destroy(nn); kvfree(nn->drc_hashtbl); nn->drc_hashtbl = NULL; diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 1c39a4e6294d..cc538b8c0287 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1458,6 +1458,9 @@ static __net_init int nfsd_init_net(struct net *net) retval = nfsd_idmap_init(net); if (retval) goto out_idmap_error; + retval = nfsd_net_reply_cache_init(nn); + if (retval) + goto out_repcache_error; nn->nfsd_versions = NULL; nn->nfsd4_minorversions = NULL; nfsd4_init_leases_net(nn); @@ -1466,6 +1469,8 @@ static __net_init int nfsd_init_net(struct net *net) return 0; +out_repcache_error: + nfsd_idmap_shutdown(net); out_idmap_error: nfsd_export_shutdown(net); out_export_error: @@ -1474,9 +1479,12 @@ static __net_init int nfsd_init_net(struct net *net) static __net_exit void nfsd_exit_net(struct net *net) { + struct nfsd_net *nn = net_generic(net, nfsd_net_id); + + nfsd_net_reply_cache_destroy(nn); nfsd_idmap_shutdown(net); nfsd_export_shutdown(net); - nfsd_netns_free_versions(net_generic(net, nfsd_net_id)); + nfsd_netns_free_versions(nn); } static struct pernet_operations nfsd_net_ops = {