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 128EE3B28D for ; Tue, 8 Sep 2026 00:46:14 +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=1788828376; cv=none; b=eHw+P0t/YgUI5k01vvCa4k8Q1K0sTABoZ0vdNwNqWSNzpLvhEE46UyRWb25EH6XVglu4SMYlQzH9IVi0wBpvgHe6K0LL8H7wcozw0we4cc7Cq5zOkkETHI19saVkyz4mRuhyqcXgINnLBcOE5W1N0YXtdIAlo6lh8xBCRc1lw18= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788828376; c=relaxed/simple; bh=p+hDeu1w2aJxETsA/5rORN6xaBv93S9rOok84T1junw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=doiyHpno2aBS44WEgPIWO2HH7oBh69cl3BIkyLLGSU51m7Cxqnwghsl0hohYfUbnm4oV7/oLnCs202e0OxLgKRj76CfOiz+zLK36SObEB7HOsxuXpxvrTVjnKPYE7X9fQwKCDMsAkDysRoCFnYTq88lxDuCYb7qJYclicFZOFWs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hW1CLNqP; 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="hW1CLNqP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 373411F00A3E; Tue, 8 Sep 2026 00:46:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788828374; bh=9ak35JRNyFr5j+VP5FAeQf3v8AVGi7SMcR/kytNdX3o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hW1CLNqP1WIAhzdTrtqD2RcYlebu5fEuVnu6pw7bbnZehKb/afktf2tyvs0k9XiMp jubi8iLUAIBUQ8v477h2X5p3SZamLY1TjY8QL1bvPl1cUlffUhmV+fEw6VgOkeyuA+ nhFe92mUxKNO3dCQGiQpvRpWjhEvIOdzLlST65Iw5kBnicHloMPe1CiQaIhMiWkkPK GXWoB86owXoV1PqHmqgKhn8ws/5WzT6nlqUT0kgBNNfGV23iJRIl+2/eqOqH4lQZ7Y 78EmyuduB7e3bJHKOyWZfWod7I8YvEo87bJfFc6fEd0PzI5ZZY5drspcnwtkq7FmJZ s4xRGtmY6LUjg== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , Jeff Layton , Sasha Levin Subject: [PATCH 6.6.y 3/3] NFSD: Prevent client use-after-free during close_lru reaping Date: Mon, 7 Sep 2026 20:46:10 -0400 Message-ID: <20260908004610.1630138-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260908004610.1630138-1-sashal@kernel.org> References: <2026090305-identical-flame-bc6a@gregkh> <20260908004610.1630138-1-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 2330b788d732f43668b965b3105b37ceb276dfea ] 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") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Link: https://patch.msgid.link/20260709-cel-v4-8-1d519d9be0cb@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/nfs4state.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 1592a9b36a344..fdd032f53f2ab 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -6310,11 +6310,16 @@ 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); -- 2.53.0