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 CFBC64195A1 for ; Thu, 9 Jul 2026 17:40:44 +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=1783618846; cv=none; b=L6SWqwvRUh4r+ZXiV7cRfAbGaox+Ripdkxzje0hd6CirT/jZN0Ap1kgh8bPPcg9xOqh3VZKNjPNc7WBMmSCmJYR9liXHCUzmoLrd1Iq4RSNZu6tJEa6C4O1L3J5ZyuB3xT9YB73X5a4MDm7zO8AujlWOqXqT/JgDl2boOZdIQd8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783618846; c=relaxed/simple; bh=7o2U8Cx6yOwoilcKjBrQS13/IIvFmFyGXMDZw0FSu1c=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=tkU+nMgyJnuJyzNrDLy/OeZCF6KzoMTAjXkJ1bE87OieROhQ2Qxjfo6wPIZw3WjdtMgVOXoe9/5/eNGTHQrk3mixYfNYuJ/RVBnq+eVKKj9qSG4WzYQQaCFtLyyAADlLF0qa1eFkoMM32GN5S9BwSB89UdGiTCVhxwrVVMWOohA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=awkniwID; 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="awkniwID" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3DB4E1F000E9; Thu, 9 Jul 2026 17:40:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783618844; bh=Wnhvk173j5CMo87oefXBHcFkS8mcYI1bcdFLa4rh8Fg=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=awkniwIDYXwa6YYZ/gWoKUYF2egdJAVgO32RHqBuSzK4Ib586XtvCa9fJ5lkLAUiy HhCS1Zr+RDOGVTiogeRekE85JrsMm2Y6ZzbUluJEBDLjZ1+8TKFbBP31bl+PODV7hG ZXr4ZpdsLHHpcE9xvZOa6D5PwtAMAakKjLG4HWJdmEh3IYlduf7iB4wdri7XsgAm/D KGrZ2T+iEfhq2YNzlQorVAznq8TUMkrLbA1RVgxWrsC3AifoxGbnEKpuTylRID2xOq zcdMupG0fqpxemeIZ7UpBz0wVPoL0GyxfmB4sIlFzFcRJ3QE3cjI8g340fTnwLrLjY fUMnKX+EhQXMw== From: Chuck Lever Date: Thu, 09 Jul 2026 13:40:31 -0400 Subject: [PATCH v4 8/9] NFSD: Prevent client use-after-free during close_lru reaping Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260709-cel-v4-8-1d519d9be0cb@kernel.org> References: <20260709-cel-v4-0-1d519d9be0cb@kernel.org> In-Reply-To: <20260709-cel-v4-0-1d519d9be0cb@kernel.org> To: Jeff Layton , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-nfs@vger.kernel.org, Chuck Lever X-Mailer: b4 0.16-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=1679; i=cel@kernel.org; h=from:subject:message-id; bh=7o2U8Cx6yOwoilcKjBrQS13/IIvFmFyGXMDZw0FSu1c=; b=owEBbQKS/ZANAwAKATNqszNvZn+XAcsmYgBqT90WeRRxATc1XPfjZWVizPz0wpp8Uq6Ai+aop 5GmEY3q1guJAjMEAAEKAB0WIQQosuWwEobfJDzyPv4zarMzb2Z/lwUCak/dFgAKCRAzarMzb2Z/ lwHSD/9WiWpnBcgwfEYu88iUYLFaRfmSoFkI0XKCHqQZRO/goJbDhamwE4cOj5a1p4zDywZ4Jzo XknQjOn9aUFEO8xwvqxhNOOSrucz0TCNVe4TMNuuOll8aJGv7dzx8vY7SghD+jmiE+Cz2iCZk3u cKhIODSsV7uI85UcpoL6lzK/YqUcgwsa9xuHP18PjhYXb5A+qRiHpKakI66YP3RlmzG+ACkTYSg ndP52Aiy9Ubv7GXq22G3fYLcOlOjUHoQyU78p5GQpn3a6gxxGwpGND/fS6Z5v8Eb5hhR6IlA1mA g6iXoDBFO/5CTAhNSrL6EtsSOHeQ7Mx/KrV+VmFabfqp/Pak7WevKZ3llwUQ2xjUyKsazrtjP9f gscNRi+TY7p6dT86wG22eFpIWHENLojRqyZA3zdiYcqXPWzHoVTv6OeyP0wtTOhsiy+1ObK0RPg gqKi9Jv5xjrcPEQ0+Qnqost503hrkMTnpF4P5K5Tui7UNbC+ANRbASZ9cBZmt/OxqPc98CPNVLZ 2mjOZYmWFETpH3q56Z3261vYS2OvdTyVBBDxLr1B92VYPcXqrlFyadiXUzp4ukSlHToA1Mcsm2K VpBesPeNtVYZlevZknTpebDIiXHrSh4DB+Jdk6UmMX3mafATjgmcLkqrT0eO/4A3/MESbxfQg9E +7E2afN+c8TNNRw== X-Developer-Key: i=cel@kernel.org; a=openpgp; fpr=28B2E5B01286DF243CF23EFE336AB3336F667F97 An nfs4_openowner left on nn->close_lru after its final CLOSE keeps its last closed stateid in oo_last_closed_stid, holding only a raw pointer to its nfs4_client. The laundromat reaps timed-out entries, drops nn->client_lock, and calls nfs4_put_stid(), which dereferences the client through cl_lock. Nothing pins the client across that window, so a concurrent force_expire_client() can free it and nfs4_put_stid() reads freed memory. __destroy_client() hits the same race, walking clp->cl_openowners without cl_lock. Pin the client with cl_rpc_users before dropping client_lock, and skip clients already expiring. __destroy_client() then cleans up its own close_lru entries through release_last_closed_stateid(), so teardown no longer races the laundromat. Fixes: 217526e7ecc9 ("nfsd: protect the close_lru list and oo_last_closed_stid with client_lock") Signed-off-by: Chuck Lever --- fs/nfsd/nfs4state.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 4acd02f1642c..20556b8f186a 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -7581,11 +7581,16 @@ nfs4_laundromat(struct nfsd_net *nn) if (!state_expired(<, oo->oo_time)) break; list_del_init(&oo->oo_close_lru); + clp = oo->oo_owner.so_client; + if (is_client_expired(clp)) + continue; stp = oo->oo_last_closed_stid; oo->oo_last_closed_stid = NULL; + atomic_inc(&clp->cl_rpc_users); spin_unlock(&nn->client_lock); nfs4_put_stid(&stp->st_stid); spin_lock(&nn->client_lock); + put_client_no_renew_locked(clp); } spin_unlock(&nn->client_lock); -- 2.54.0