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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 68A2CC10DCE for ; Sun, 15 Mar 2020 09:30:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 73E1F206BE for ; Sun, 15 Mar 2020 09:30:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TzL2mRYJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728139AbgCOJa1 (ORCPT ); Sun, 15 Mar 2020 05:30:27 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:37553 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726521AbgCOJa1 (ORCPT ); Sun, 15 Mar 2020 05:30:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584264625; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rNFz5DYWHgexHyJt056VriaIF9paJuhnZXXnkdcdqbg=; b=TzL2mRYJKAgXMfNkumr72/yUVM9jkNg8ca4qTRUeRNaZqDYEWaFeqlhuBt5dpVK5jVFt1T uYLVuO6BM7/jv2IqhfgdRNMSlcE6N93R7CQX6AQgvR1tpYZDhleqKwSu7sdwXwjNdGgR+f lkym10VwmfyPJ8af6z07X20tRFZvHVA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-460-1ULkcQfGN8SlH9l2u-WY7w-1; Sun, 15 Mar 2020 05:30:21 -0400 X-MC-Unique: 1ULkcQfGN8SlH9l2u-WY7w-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9F24B107ACC7; Sun, 15 Mar 2020 09:30:19 +0000 (UTC) Received: from krava (ovpn-204-71.brq.redhat.com [10.40.204.71]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7D467907F7; Sun, 15 Mar 2020 09:30:16 +0000 (UTC) Date: Sun, 15 Mar 2020 10:30:13 +0100 From: Jiri Olsa To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Namhyung Kim , LKML , clang-built-linux , Stephane Eranian Subject: Re: [PATCH] perf mem2node: avoid double free related to realloc Message-ID: <20200315093013.GC492969@krava> References: <20200314042826.166953-1-irogers@google.com> <20200314142332.GB492969@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 14, 2020 at 09:49:37AM -0700, Ian Rogers wrote: > On Sat, Mar 14, 2020 at 7:23 AM Jiri Olsa wrote: > > > > On Fri, Mar 13, 2020 at 09:28:26PM -0700, Ian Rogers wrote: > > > Realloc of size zero is a free not an error, avoid this causing a double > > > free. Caught by clang's address sanitizer: > > > > > > ==2634==ERROR: AddressSanitizer: attempting double-free on 0x6020000015f0 in thread T0: > > > #0 0x5649659297fd in free llvm/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:123:3 > > > #1 0x5649659e9251 in __zfree tools/lib/zalloc.c:13:2 > > > #2 0x564965c0f92c in mem2node__exit tools/perf/util/mem2node.c:114:2 > > > #3 0x564965a08b4c in perf_c2c__report tools/perf/builtin-c2c.c:2867:2 > > > #4 0x564965a0616a in cmd_c2c tools/perf/builtin-c2c.c:2989:10 > > > #5 0x564965944348 in run_builtin tools/perf/perf.c:312:11 > > > #6 0x564965943235 in handle_internal_command tools/perf/perf.c:364:8 > > > #7 0x5649659440c4 in run_argv tools/perf/perf.c:408:2 > > > #8 0x564965942e41 in main tools/perf/perf.c:538:3 > > > > > > 0x6020000015f0 is located 0 bytes inside of 1-byte region [0x6020000015f0,0x6020000015f1) > > > freed by thread T0 here: > > > #0 0x564965929da3 in realloc third_party/llvm/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3 > > > #1 0x564965c0f55e in mem2node__init tools/perf/util/mem2node.c:97:16 > > > #2 0x564965a08956 in perf_c2c__report tools/perf/builtin-c2c.c:2803:8 > > > #3 0x564965a0616a in cmd_c2c tools/perf/builtin-c2c.c:2989:10 > > > #4 0x564965944348 in run_builtin tools/perf/perf.c:312:11 > > > #5 0x564965943235 in handle_internal_command tools/perf/perf.c:364:8 > > > #6 0x5649659440c4 in run_argv tools/perf/perf.c:408:2 > > > #7 0x564965942e41 in main tools/perf/perf.c:538:3 > > > > > > previously allocated by thread T0 here: > > > #0 0x564965929c42 in calloc third_party/llvm/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:154:3 > > > #1 0x5649659e9220 in zalloc tools/lib/zalloc.c:8:9 > > > #2 0x564965c0f32d in mem2node__init tools/perf/util/mem2node.c:61:12 > > > #3 0x564965a08956 in perf_c2c__report tools/perf/builtin-c2c.c:2803:8 > > > #4 0x564965a0616a in cmd_c2c tools/perf/builtin-c2c.c:2989:10 > > > #5 0x564965944348 in run_builtin tools/perf/perf.c:312:11 > > > #6 0x564965943235 in handle_internal_command tools/perf/perf.c:364:8 > > > #7 0x5649659440c4 in run_argv tools/perf/perf.c:408:2 > > > #8 0x564965942e41 in main tools/perf/perf.c:538:3 > > > > > > Signed-off-by: Ian Rogers > > > --- > > > tools/perf/util/mem2node.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/tools/perf/util/mem2node.c b/tools/perf/util/mem2node.c > > > index 797d86a1ab09..7f97aa69eb65 100644 > > > --- a/tools/perf/util/mem2node.c > > > +++ b/tools/perf/util/mem2node.c > > > @@ -95,7 +95,7 @@ int mem2node__init(struct mem2node *map, struct perf_env *env) > > > > > > /* Cut unused entries, due to merging. */ > > > tmp_entries = realloc(entries, sizeof(*entries) * j); > > > - if (tmp_entries) > > > + if (j == 0 || tmp_entries) > > > > nice catch.. I wonder if we should fail in here, or at least > > warn that there're no entris.. which is really strange ;-) > > The workload was the stream benchmark with perf c2c, but stream isn't > particularly long running. Not sure how j became 0, there's 2 > possibilities in the code. The worry with a warning is the spam, so I > just wanted to make the code correct. I was wondering if we should fail completely, but we might break some c2c expected behaviour how about just WARN_ONCE pn j == 0, and then the lookup will fail already with: if (WARN_ONCE(node < 0, "WARNING: failed to find node\n")) return; just get enough hints ;-) jirka > > Thanks, > Ian > > > thanks, > > jirka > > > > > entries = tmp_entries; > > > > > > for (i = 0; i < j; i++) { > > > -- > > > 2.25.1.481.gfbce0eb801-goog > > > > > >