From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751491AbcFKB3J (ORCPT ); Fri, 10 Jun 2016 21:29:09 -0400 Received: from mail.kernel.org ([198.145.29.136]:52982 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751016AbcFKB3H (ORCPT ); Fri, 10 Jun 2016 21:29:07 -0400 Date: Sat, 11 Jun 2016 10:28:55 +0900 From: Masami Hiramatsu To: Wang Nan Cc: , , , , Arnaldo Carvalho de Melo Subject: Re: [PATCH] perf tools: Fix crash in build_id_cache__kallsyms_path() Message-Id: <20160611102855.9b17979d58a0ab42d581cb48@kernel.org> In-Reply-To: <1465271678-7392-1-git-send-email-wangnan0@huawei.com> References: <1465271678-7392-1-git-send-email-wangnan0@huawei.com> X-Mailer: Sylpheed 3.4.3 (GTK+ 2.24.28; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 7 Jun 2016 03:54:38 +0000 Wang Nan wrote: > build_id_cache__kallsyms_path() accept string buffer but also alloc buffer > by itself using asnprintf. Unfortunately, the only user of it passes it > a stack-allocated buffer. Freeing it causes crash like this: > > $ perf script > *** Error in `/home/wangnan/perf': free(): invalid pointer: 0x00007fffffff9630 *** > ======= Backtrace: ========= > lib64/libc.so.6(+0x6eeef)[0x7ffff5dbaeef] > lib64/libc.so.6(+0x78cae)[0x7ffff5dc4cae] > lib64/libc.so.6(+0x79987)[0x7ffff5dc5987] > /home/w00229757/perf(build_id_cache__kallsyms_path+0x6b)[0x49681b] > /home/w00229757/perf[0x4bdd40] > /home/w00229757/perf(dso__load+0xa3a)[0x4c048a] > /home/w00229757/perf(map__load+0x6f)[0x4d561f] > /home/w00229757/perf(thread__find_addr_map+0x235)[0x49e935] > /home/w00229757/perf(machine__resolve+0x7d)[0x49ec6d] > /home/w00229757/perf[0x4555a8] > /home/w00229757/perf[0x4d9507] > /home/w00229757/perf[0x4d9e80] > /home/w00229757/perf(ordered_events__flush+0x354)[0x4dd444] > /home/w00229757/perf(perf_session__process_events+0x3d0)[0x4dc140] > /home/w00229757/perf(cmd_script+0x12b0)[0x4592e0] > /home/w00229757/perf[0x4911f1] > /home/w00229757/perf(main+0x68f)[0x4352ef] > /lib64/libc.so.6(__libc_start_main+0xf5)[0x7ffff5d6dbd5] > /home/w00229757/perf[0x435415] > ======= Memory map: ======== > > This patch simplify build_id_cache__kallsyms_path(), don't even consider > allocate string buffer, so never free anything. The caller of it should > management memory allocation. > > Signed-off-by: Wang Nan > Cc: Masami Hiramatsu > Cc: Arnaldo Carvalho de Melo > Fixes: 01412261d994 ("perf buildid-cache: Use path/to/bin/buildid/elf instead of path/to/bin/buildid") > --- > tools/perf/util/build-id.c | 11 ++++------- > 1 file changed, 4 insertions(+), 7 deletions(-) > > diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c > index 67f986c..20aef90 100644 > --- a/tools/perf/util/build-id.c > +++ b/tools/perf/util/build-id.c > @@ -147,20 +147,17 @@ static int asnprintf(char **strp, size_t size, const char *fmt, ...) > char *build_id_cache__kallsyms_path(const char *sbuild_id, char *bf, > size_t size) > { > - bool is_alloc = !!bf; Oops, I think this is the reason why it failed. is_alloc should be !bf (means allocation needed) > bool retry_old = true; > > - asnprintf(&bf, size, "%s/%s/%s/kallsyms", > - buildid_dir, DSO__NAME_KALLSYMS, sbuild_id); > + snprintf(bf, size, "%s/%s/%s/kallsyms", > + buildid_dir, DSO__NAME_KALLSYMS, sbuild_id); > retry: > if (!access(bf, F_OK)) > return bf; > - if (is_alloc) > - free(bf); Then, it works well. Thanks, > if (retry_old) { > /* Try old style kallsyms cache */ > - asnprintf(&bf, size, "%s/%s/%s", > - buildid_dir, DSO__NAME_KALLSYMS, sbuild_id); > + snprintf(bf, size, "%s/%s/%s", > + buildid_dir, DSO__NAME_KALLSYMS, sbuild_id); > retry_old = false; > goto retry; > } > -- > 1.8.3.4 > -- Masami Hiramatsu