From patchwork Tue Apr 11 21:17:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beau Belgrave X-Patchwork-Id: 13208266 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 039EEC76196 for ; Tue, 11 Apr 2023 21:17:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229759AbjDKVRR (ORCPT ); Tue, 11 Apr 2023 17:17:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229736AbjDKVRQ (ORCPT ); Tue, 11 Apr 2023 17:17:16 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 91CFF3594; Tue, 11 Apr 2023 14:17:15 -0700 (PDT) Received: from W11-BEAU-MD.localdomain (unknown [76.135.27.212]) by linux.microsoft.com (Postfix) with ESMTPSA id C741921779A1; Tue, 11 Apr 2023 14:17:14 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com C741921779A1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1681247834; bh=oBm7UAgWYx2ikyJKWEAABOUG7UTL+PiB3Yh06pGj3g4=; h=From:To:Cc:Subject:Date:From; b=Z1at4qah8WLFhkDhgppqXLfGtmJesTfcpCqNdRs5uL5vtv/r8RSyI0GKqfIvr2IM+ RZiEH9lth5WwyGRJaJ5ISnlyjQw5e8CTtosRcPVUqH8MIPC/g0V9CpadyRFfnvEke+ TLuscezLrkws+N7xej1QA+SxPkUXprULy2b1C0zk= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, dcook@linux.microsoft.com, alanau@linux.microsoft.com Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH 0/3] tracing/user_events: Fixes and improvements for 6.4 Date: Tue, 11 Apr 2023 14:17:06 -0700 Message-Id: <20230411211709.15018-1-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org Now that user_events is in for-next we broadened our integration of user_events. During this integration we found a few things that can help prevent the debugging of issues for user_events when user processes use the ABI directly. The most important thing found is an out of bounds fix with the write index. If it is negative, an out of bounds access is attempted. This bug was introduced on one of the very first user_events patches and remained unseen for a long time. Apologies for not catching that sooner. We think users will expect the kernel to always clear the registered bit when events are unregistered, even if the event is still enabled in a kernel tracer. The user process could do this after unregistering, but it seems appropriate for the kernel side to attempt this. We also discussed if it makes sense for the kernel to allow user processes to tie multiple events to the same value and bit. While this doesn't cause any issues on the kernel side, it leads to very undefined behavior for the user process. Depending on which event gets enabled when, the bit will vary. Beau Belgrave (3): tracing/user_events: Ensure write index cannot be negative tracing/user_events: Ensure bit is cleared on unregister tracing/user_events: Prevent same address and bit per process kernel/trace/trace_events_user.c | 77 +++++++++++++++++++ .../testing/selftests/user_events/abi_test.c | 9 ++- .../selftests/user_events/ftrace_test.c | 14 +++- 3 files changed, 96 insertions(+), 4 deletions(-) base-commit: 88fe1ec75fcb296579e05eaf3807da3ee83137e4