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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1F20BC61DB3 for ; Fri, 6 Jan 2023 21:12:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236208AbjAFVMu (ORCPT ); Fri, 6 Jan 2023 16:12:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52422 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229698AbjAFVMp (ORCPT ); Fri, 6 Jan 2023 16:12:45 -0500 Received: from mail-wm1-f41.google.com (mail-wm1-f41.google.com [209.85.128.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A81A81C30; Fri, 6 Jan 2023 13:12:41 -0800 (PST) Received: by mail-wm1-f41.google.com with SMTP id bi26-20020a05600c3d9a00b003d3404a89faso4203545wmb.1; Fri, 06 Jan 2023 13:12:41 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=M0S5RcjIuN5LkBKmRcLV/E57EqVNGtJupTeqbW7E1Gw=; b=62ESpyLv7zBJ3ZDrd81/QWN7Fe3qQQlJwgUECCWy3VEXd7DDJh3Sv4SF4GJ9C2pg6B emaeLQzJzJ6kICaEaZhlbZZ4jf/1CYEcrG7e5NEy0fBt6VHKQ55APxpvNoLCqkfHLGC8 j3/6pIUTdgRoWVp302vMp6Yre0OB2InJ/F3TWDf6IZB8fwpdiOU8kAAp3E1MnD5P0GQW BpopmRlXWiZcShwvl9tTVjzY4E0zS6Fk3HFuK986/eU4Tk6+EBTzLDeLBD6eis3fANOo 3rJ7gRqfsITxTP6In53EniTp9WT8JTE3lITgYyOakCZgDfMTCD42b7eclyG2wRZVOfvu sWFQ== X-Gm-Message-State: AFqh2kpQbgKr7aIYUed8oS52izvE6kSdEt0HZDlcwBgtqTTtUsmlNU/N lYQrWbPLQ3JHlbKc90QFgpSek/56AXCWuP3ezbI= X-Google-Smtp-Source: AMrXdXvUcf6XaCNU/zlLzwQ0hiws4g6C8DzMr8eSF6s+BszD7xrhT9eh8zSNNp01rrMrscbF+UDe9o0a0PewL+zC/Os= X-Received: by 2002:a05:600c:510f:b0:3d0:5160:e0e2 with SMTP id o15-20020a05600c510f00b003d05160e0e2mr2192799wms.147.1673039559931; Fri, 06 Jan 2023 13:12:39 -0800 (PST) MIME-Version: 1.0 References: <20221229124728.66515-1-yangjihong1@huawei.com> In-Reply-To: From: Namhyung Kim Date: Fri, 6 Jan 2023 13:12:28 -0800 Message-ID: Subject: Re: [PATCH v2] perf record: Fix coredump with --overwrite and --max-size To: Yang Jihong Cc: Arnaldo Carvalho de Melo , peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, jiwei.sun@windriver.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Jan 4, 2023 at 8:09 PM Yang Jihong wrote: > > Hello, > > On 2023/1/4 0:50, Namhyung Kim wrote: > > On Mon, Jan 2, 2023 at 8:20 AM Arnaldo Carvalho de Melo wrote: > >> > >> Em Thu, Dec 29, 2022 at 12:47:28PM +0000, Yang Jihong escreveu: > >>> When --overwrite and --max-size options of perf record are used together, > >>> a segmentation fault occurs. The following is an example: > >>> > >>> # perf record -e sched:sched* --overwrite --max-size 1M -a -- sleep 1 > >>> [ perf record: Woken up 1 times to write data ] > >>> perf: Segmentation fault > >>> Obtained 1 stack frames. > >>> [0xc4c67f] > >>> Segmentation fault (core dumped) > >>> > >>> backtrace of the core file is as follows: > >>> > >>> #0 0x0000000000417990 in process_locked_synthesized_event (tool=0x0, event=0x15, sample=0x1de0, machine=0xf8) at builtin-record.c:630 > >>> #1 0x000000000057ee53 in perf_event__synthesize_threads (nr_threads_synthesize=21, mmap_data=, needs_mmap=, machine=0x17ad9b0, process=, tool=0x0) at util/synthetic-events.c:1950 > >>> #2 __machine__synthesize_threads (nr_threads_synthesize=0, data_mmap=, needs_mmap=, process=, threads=0x8, target=0x8, tool=0x0, machine=0x17ad9b0) at util/synthetic-events.c:1936 > >>> #3 machine__synthesize_threads (machine=0x17ad9b0, target=0x8, threads=0x8, needs_mmap=, data_mmap=, nr_threads_synthesize=0) at util/synthetic-events.c:1947 > >>> #4 0x000000000040165d in record__synthesize (tail=, rec=0xbe2520 ) at builtin-record.c:2010 > >>> #5 0x0000000000403989 in __cmd_record (argc=, argv=, rec=0xbe2520 ) at builtin-record.c:2810 > >>> #6 0x00000000004196ba in record__init_thread_user_masks (rec=0xbe2520 , cpus=0x17a65f0) at builtin-record.c:3837 > >>> #7 record__init_thread_masks (rec=0xbe2520 ) at builtin-record.c:3938 > >>> #8 cmd_record (argc=1, argv=0x7ffdd692dc60) at builtin-record.c:4241 > >>> #9 0x00000000004b701d in pager_command_config (var=0x0, value=0x15 , data=0x1de0) at perf.c:117 > >>> #10 0x00000000004b732b in get_leaf_frame_caller_aarch64 (sample=0xfffffffb, thread=0x0, usr_idx=) at util/arm64-frame-pointer-unwind-support.c:56 > >>> #11 0x0000000000406331 in execv_dashed_external (argv=0x7ffdd692d9e8) at perf.c:410 > >>> #12 run_argv (argcp=, argv=) at perf.c:431 > >>> #13 main (argc=, argv=0x7ffdd692d9e8) at perf.c:562 > >>> > >>> The reason is that record__bytes_written accesses the freed memory rec->thread_data, > >>> The process is as follows: > >>> __cmd_record > >>> -> record__free_thread_data > >>> -> zfree(&rec->thread_data) // free rec->thread_data > >>> -> record__synthesize > >>> -> perf_event__synthesize_id_index > >>> -> process_synthesized_event > >>> -> record__write > >>> -> record__bytes_written // access rec->thread_data > >>> > >>> we only need to check the value of done first. > >>> Also add variable check in record__bytes_written for code hardening, > >>> and save bytes_written separately to reduce one calculation. > >>> > >>> Fixes: 6d57581659f7 ("perf record: Add support for limit perf output file size") > >>> Signed-off-by: Yang Jihong > >>> --- > >>> > >>> Changes since v1: > >>> - Add variable check in record__bytes_written for code hardening. > >>> - Save bytes_written separately to reduce one calculation. > >>> - Remove rec->opts.tail_synthesize check. > >> > >> Namhyung, are you ok with this now? > >> > >> - Arnaldo > >> > >>> tools/perf/builtin-record.c | 26 +++++++++++++++++--------- > >>> 1 file changed, 17 insertions(+), 9 deletions(-) > >>> > >>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > >>> index 29dcd454b8e2..acba9e43e519 100644 > >>> --- a/tools/perf/builtin-record.c > >>> +++ b/tools/perf/builtin-record.c > >>> @@ -230,16 +230,29 @@ static u64 record__bytes_written(struct record *rec) > >>> u64 bytes_written = rec->bytes_written; > >>> struct record_thread *thread_data = rec->thread_data; > >>> > >>> + if (thread_data == NULL) > >>> + return bytes_written; > >>> + > > > > Then it won't count bytes written by threads, right? > > I think it needs to be saved somewhere. > > > I'm not sure here. Can you explain it more clearly, thanks :) > I can modify it accordingly. > > I think if thread_data == NULL, it is not thread data. > In this case, we just return rec->bytes_written. It can be thread data but freed before tail synthesis, right? In that case, I think it needs to add bytes_written by threads to calculate the correct data size. Thanks, Namhyung