From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2572DC48BE8 for ; Mon, 24 Jun 2019 10:02:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1FD7212F5 for ; Mon, 24 Jun 2019 10:02:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561370534; bh=plZOkWaLb4yy5BvUkpSJ/NwGDi97Ob4vcXUWQKp9oBk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=WyvKIliZEMKF8clHe1vhvHpvC9YYeHPHZgu7S+iA0IkYQgjBT5eJkB5pTu0t3O5iU j8POjzQ2AEVm0ll+FNaIcGTMSYTwHdnRkwfcGxI04U1V+xr6d61bYlF0OHVPDsj2Ux KUzYnGAaavH3LeGWz34yKN/YYcEHhkmRw9GN1694= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729082AbfFXKCN (ORCPT ); Mon, 24 Jun 2019 06:02:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:33266 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727284AbfFXKCM (ORCPT ); Mon, 24 Jun 2019 06:02:12 -0400 Received: from localhost (f4.8f.5177.ip4.static.sl-reverse.com [119.81.143.244]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 10A072146F; Mon, 24 Jun 2019 10:02:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561370531; bh=plZOkWaLb4yy5BvUkpSJ/NwGDi97Ob4vcXUWQKp9oBk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nVmf+DgRrS80lvELxEXOMQXLL8FXWOc7K9UG+zShHIidJLwCROIbPW+AF/C6gBLla 8ifXyktGhMBH5jvmd4R9jur64WAVwChhMVOv/Vwtp1Aufebv7RtmNSmz7ORmzmWkS5 jJHmRBJXbobIWWtC5cBLVRcmXpVVIm/WqW3aRE7M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Miguel Ojeda , "Steven Rostedt (VMware)" Subject: [PATCH 4.19 01/90] tracing: Silence GCC 9 array bounds warning Date: Mon, 24 Jun 2019 17:55:51 +0800 Message-Id: <20190624092313.930230995@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190624092313.788773607@linuxfoundation.org> References: <20190624092313.788773607@linuxfoundation.org> User-Agent: quilt/0.66 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Miguel Ojeda commit 0c97bf863efce63d6ab7971dad811601e6171d2f upstream. Starting with GCC 9, -Warray-bounds detects cases when memset is called starting on a member of a struct but the size to be cleared ends up writing over further members. Such a call happens in the trace code to clear, at once, all members after and including `seq` on struct trace_iterator: In function 'memset', inlined from 'ftrace_dump' at kernel/trace/trace.c:8914:3: ./include/linux/string.h:344:9: warning: '__builtin_memset' offset [8505, 8560] from the object at 'iter' is out of the bounds of referenced subobject 'seq' with type 'struct trace_seq' at offset 4368 [-Warray-bounds] 344 | return __builtin_memset(p, c, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ In order to avoid GCC complaining about it, we compute the address ourselves by adding the offsetof distance instead of referring directly to the member. Since there are two places doing this clear (trace.c and trace_kdb.c), take the chance to move the workaround into a single place in the internal header. Link: http://lkml.kernel.org/r/20190523124535.GA12931@gmail.com Signed-off-by: Miguel Ojeda [ Removed unnecessary parenthesis around "iter" ] Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 6 +----- kernel/trace/trace.h | 18 ++++++++++++++++++ kernel/trace/trace_kdb.c | 6 +----- 3 files changed, 20 insertions(+), 10 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8351,12 +8351,8 @@ void ftrace_dump(enum ftrace_dump_mode o cnt++; - /* reset all but tr, trace, and overruns */ - memset(&iter.seq, 0, - sizeof(struct trace_iterator) - - offsetof(struct trace_iterator, seq)); + trace_iterator_reset(&iter); iter.iter_flags |= TRACE_FILE_LAT_FMT; - iter.pos = -1; if (trace_find_next_entry_inc(&iter) != NULL) { int ret; --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1895,4 +1895,22 @@ static inline void tracer_hardirqs_off(u extern struct trace_iterator *tracepoint_print_iter; +/* + * Reset the state of the trace_iterator so that it can read consumed data. + * Normally, the trace_iterator is used for reading the data when it is not + * consumed, and must retain state. + */ +static __always_inline void trace_iterator_reset(struct trace_iterator *iter) +{ + const size_t offset = offsetof(struct trace_iterator, seq); + + /* + * Keep gcc from complaining about overwriting more than just one + * member in the structure. + */ + memset((char *)iter + offset, 0, sizeof(struct trace_iterator) - offset); + + iter->pos = -1; +} + #endif /* _LINUX_KERNEL_TRACE_H */ --- a/kernel/trace/trace_kdb.c +++ b/kernel/trace/trace_kdb.c @@ -41,12 +41,8 @@ static void ftrace_dump_buf(int skip_lin kdb_printf("Dumping ftrace buffer:\n"); - /* reset all but tr, trace, and overruns */ - memset(&iter.seq, 0, - sizeof(struct trace_iterator) - - offsetof(struct trace_iterator, seq)); + trace_iterator_reset(&iter); iter.iter_flags |= TRACE_FILE_LAT_FMT; - iter.pos = -1; if (cpu_file == RING_BUFFER_ALL_CPUS) { for_each_tracing_cpu(cpu) {