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 453D323E25B for ; Tue, 8 Sep 2026 01:13:37 +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=1788830018; cv=none; b=EvDBEpL27vLOHZrSBxHVvgNyF6Ibdr4oqfxNH2qy+bCwku1fA7tgI6ArP6Gu3veFgPlpXen2Xu8qJt8LsYCDqrSiy/Mbv/TrGfAdZOY+dwxrHukypsTZttlyAyDcm+hxqdqLeVFVKuVaVc8bxE04KTePWQKgkgHwhZtBznnu4E8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788830018; c=relaxed/simple; bh=RshXthxqv02AQfDyoiAVHgD4ZZ4xe4RmGDWIjQauGME=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lKx2/yxBQw1koioCEPfqPS5Es90WMT0mVuvreiw3U4UutjCLBHUNUQvuZKNKLOlpS4y6IrPeah9b8MVfaMSASdtTwy3r5sNfIhcV2Qc0dRW9fxPZNfL9yA0fUcExGjDXlGre18BEIZPpAwKCt4wAI/uk4yr9iSvMmAzftvdqEC0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UVPwlfbu; 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="UVPwlfbu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F3601F00A3F; Tue, 8 Sep 2026 01:13:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788830016; bh=VlubY8e8npCuNlH0BvKWftqRGCJzEjCRhyFpzISRqfE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UVPwlfbupdcKaIuOhUaRW8g5zPbwYga/QCpf4moIibXbslPeyK3T0we+A7Iejv2UT 9FdzEkVGetGmq1gsaPrD4sc2sUDzHgyR6O1+mn4eyei1ezwyoei8vSfEzOiBrDtcuw Ketx5KDcGkwXfZQIOgzjnk+I97k1wUcKSYDfBzDCpdyhxm9g2zoqn7VJCw+56xsBu2 cDyM5Q6MDSBHxZPSM8pY+UZWUHD9Co24FNG63HvUTDaBqpOGoVkM03Aq6ynRvZZ8/O MdnAHPhuS+8gHTewfud4Zi/K+ey20qnfxF7sKrBjKHoujmzgKDi0i4uqTbDbVT7PYA CY/fkH/7YzNQA== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , NeilBrown , Jeff Layton , Sasha Levin Subject: [PATCH 5.15.y 2/3] NFSD: Consolidate the revocation-path client unpin Date: Mon, 7 Sep 2026 21:13:32 -0400 Message-ID: <20260908011333.1693596-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260908011333.1693596-1-sashal@kernel.org> References: <2026090333-gutter-request-d440@gregkh> <20260908011333.1693596-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chuck Lever [ Upstream commit 3308cf3f11ed23c79f9f3f90b34bbbad3e3a6ea9 ] The client use-after-free fixes in the state-revocation paths left four open-coded copies of one idiom: drop a cl_rpc_users pin without renewing the client's lease, waking force_expire_client() when the last pin drops on a client it is tearing down. The accompanying "do not renew" rationale was documented at only one of the four sites. put_client_renew_locked() and put_client_renew() already carry the same pin-drop logic, but they renew a non-expired client's lease and so would resurrect the client whose state is being revoked. Factor the common pin-drop into __put_client_locked(), parameterized by whether to renew. The renew helpers pass true; the new put_client_no_renew_locked() and put_client_no_renew() pass false and carry the revocation paths, which must not revive the client they are tearing down. No change in behavior. Reviewed-by: NeilBrown Reviewed-by: Jeff Layton Link: https://patch.msgid.link/20260709-cel-v4-6-1d519d9be0cb@kernel.org Signed-off-by: Chuck Lever Stable-dep-of: 9026932ac8be ("NFSD: Prevent client use-after-free during blocked-lock reaping") Signed-off-by: Sasha Levin --- fs/nfsd/nfs4state.c | 47 +++++++++++++++++++++++++++------------------ 1 file changed, 28 insertions(+), 19 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index a29b7e317b16a..4468c24145687 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -205,18 +205,28 @@ renew_client_locked(struct nfs4_client *clp) clp->cl_state = NFSD4_ACTIVE; } +/* + * Finish a cl_rpc_users unpin with the client_lock held. A + * revocation walk clears @renew so the client whose state it is + * revoking is not revived; every other caller renews the lease of + * a still-active client. + */ +static void __put_client_locked(struct nfs4_client *clp, bool renew) +{ + if (is_client_expired(clp)) + wake_up_all(&expiry_wq); + else if (renew) + renew_client_locked(clp); +} + static void put_client_renew_locked(struct nfs4_client *clp) { struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id); lockdep_assert_held(&nn->client_lock); - if (!atomic_dec_and_test(&clp->cl_rpc_users)) - return; - if (!is_client_expired(clp)) - renew_client_locked(clp); - else - wake_up_all(&expiry_wq); + if (atomic_dec_and_test(&clp->cl_rpc_users)) + __put_client_locked(clp, true); } static void put_client_renew(struct nfs4_client *clp) @@ -225,10 +235,17 @@ static void put_client_renew(struct nfs4_client *clp) if (!atomic_dec_and_lock(&clp->cl_rpc_users, &nn->client_lock)) return; - if (!is_client_expired(clp)) - renew_client_locked(clp); - else - wake_up_all(&expiry_wq); + __put_client_locked(clp, true); + spin_unlock(&nn->client_lock); +} + +static void put_client_no_renew(struct nfs4_client *clp) +{ + struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id); + + if (!atomic_dec_and_lock(&clp->cl_rpc_users, &nn->client_lock)) + return; + __put_client_locked(clp, false); spin_unlock(&nn->client_lock); } @@ -6232,15 +6249,7 @@ nfs4_laundromat(struct nfsd_net *nn) clp = dp->dl_stid.sc_client; list_del_init(&dp->dl_recall_lru); revoke_delegation(dp); - /* - * Unpin without renewing: put_client_renew() would - * renew the reaped client's lease. - */ - if (atomic_dec_and_lock(&clp->cl_rpc_users, &nn->client_lock)) { - if (is_client_expired(clp)) - wake_up_all(&expiry_wq); - spin_unlock(&nn->client_lock); - } + put_client_no_renew(clp); } spin_lock(&nn->client_lock); -- 2.53.0