From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752198AbdF0HYK (ORCPT ); Tue, 27 Jun 2017 03:24:10 -0400 Received: from terminus.zytor.com ([65.50.211.136]:57457 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751492AbdF0HYD (ORCPT ); Tue, 27 Jun 2017 03:24:03 -0400 Date: Tue, 27 Jun 2017 00:21:49 -0700 From: tip-bot for Jiri Olsa Message-ID: Cc: hpa@zytor.com, jolsa@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, mingo@kernel.org, namhyung@kernel.org, dsahern@gmail.com, acme@redhat.com, mpetlan@redhat.com Reply-To: namhyung@kernel.org, dsahern@gmail.com, mingo@kernel.org, mpetlan@redhat.com, acme@redhat.com, jolsa@kernel.org, hpa@zytor.com, tglx@linutronix.de, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl In-Reply-To: <20170626095153.553-1-jolsa@kernel.org> References: <20170626095153.553-1-jolsa@kernel.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf machine: Fix segfault for kernel.kptr_restrict=2 Git-Commit-ID: 3f938ee2f6c4fff8d95b24636a0964b5a93cf547 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 3f938ee2f6c4fff8d95b24636a0964b5a93cf547 Gitweb: http://git.kernel.org/tip/3f938ee2f6c4fff8d95b24636a0964b5a93cf547 Author: Jiri Olsa AuthorDate: Mon, 26 Jun 2017 11:51:53 +0200 Committer: Arnaldo Carvalho de Melo CommitDate: Mon, 26 Jun 2017 11:52:37 -0300 perf machine: Fix segfault for kernel.kptr_restrict=2 Michael reported the segfault when kernel.kptr_restrict=2 is set. $ perf record ls ... perf: Segmentation fault Obtained 16 stack frames. ./perf(dump_stack+0x2d) [0x5068df] ./perf(sighandler_dump_stack+0x2d) [0x5069bf] ./perf() [0x43e47b] /lib64/libc.so.6(+0x3594f) [0x7f762004794f] /lib64/libc.so.6(strlen+0x26) [0x7f762009ef86] /lib64/libc.so.6(__strdup+0xd) [0x7f762009ecbd] ./perf(maps__set_kallsyms_ref_reloc_sym+0x4d) [0x51590f] ./perf(machine__create_kernel_maps+0x136) [0x50a7de] ./perf(perf_session__create_kernel_maps+0x2c) [0x510a81] ./perf(perf_session__new+0x13d) [0x510e23] ./perf() [0x43fd61] ./perf(cmd_record+0x704) [0x441823] ./perf() [0x4bc1a0] ./perf() [0x4bc40d] ./perf() [0x4bc55f] ./perf(main+0x2d5) [0x4bc939] Segmentation fault (core dumped) The reason is that with kernel.kptr_restrict=2, we don't get the symbol from machine__get_running_kernel_start, which we want to use in maps__set_kallsyms_ref_reloc_sym and we crash. Check the symbol name value before calling maps__set_kallsyms_ref_reloc_sym() and succeed without ref_reloc_sym being set. It's safe because we check its existence before we use it. Reported-by: Michael Petlan Signed-off-by: Jiri Olsa Tested-by: Arnaldo Carvalho de Melo Cc: David Ahern Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20170626095153.553-1-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/machine.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index d7f31cb..5de2b86 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -1209,10 +1209,12 @@ int machine__create_kernel_maps(struct machine *machine) */ map_groups__fixup_end(&machine->kmaps); - if (machine__get_running_kernel_start(machine, &name, &addr)) { - } else if (maps__set_kallsyms_ref_reloc_sym(machine->vmlinux_maps, name, addr)) { - machine__destroy_kernel_maps(machine); - return -1; + if (!machine__get_running_kernel_start(machine, &name, &addr)) { + if (name && + maps__set_kallsyms_ref_reloc_sym(machine->vmlinux_maps, name, addr)) { + machine__destroy_kernel_maps(machine); + return -1; + } } return 0;