From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754857AbcA3CrU (ORCPT ); Fri, 29 Jan 2016 21:47:20 -0500 Received: from szxga01-in.huawei.com ([58.251.152.64]:52501 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753158AbcA3CrS (ORCPT ); Fri, 29 Jan 2016 21:47:18 -0500 Subject: Re: [PATCH v2] locktorture: Fix NULL pointer when torture_type is invalid To: "Paul E . McKenney" , References: <1453955159-23216-1-git-send-email-wangkefeng.wang@huawei.com> CC: , , Josh Triplett , "Guohanjun (Hanjun Guo)" From: Kefeng Wang Message-ID: <56AC2421.7020006@huawei.com> Date: Sat, 30 Jan 2016 10:46:57 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <1453955159-23216-1-git-send-email-wangkefeng.wang@huawei.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.177.19.180] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020202.56AC2430.010E,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 6e0cf938adb5ef7f5022f5db31486df0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Paul, On 2016/1/28 12:25, Kefeng Wang wrote: > Insmod locktorture with torture_type=mutex will lead to crash, > > Unable to handle kernel NULL pointer dereference at virtual address 00000008 > pgd = ffffffc0f6c10000 > [00000008] *pgd=000000013b221003, *pud=000000013b221003, *pmd=0000000000000000a > Internal error: Oops: 94000006 [#1] PREEMPT SMP > Modules linked in: locktorture(+) torture > CPU: 2 PID: 1462 Comm: insmod Not tainted 4.4.0+ #19 > Hardware name: linux,dummy-virt (DT) > task: ffffffc0fb2b3700 ti: ffffffc0fa938000 task.ti: ffffffc0fa938000 > PC is at __torture_print_stats+0x18/0x180 [locktorture] > LR is at lock_torture_stats_print+0x68/0x110 [locktorture] > pc : [] lr : [] pstate: 60000145 > sp : ffffffc0fa93bb20 > [snip...] > Call trace: > [] __torture_print_stats+0x18/0x180 [locktorture] > [] lock_torture_stats_print+0x68/0x110 [locktorture] > [] lock_torture_cleanup+0xc4/0x278 [locktorture] > [] lock_torture_init+0x144/0x5b0 [locktorture] > [] do_one_initcall+0x94/0x1a0 > [] do_init_module+0x60/0x1c8 > [] load_module+0x1880/0x1c9c > [] SyS_finit_module+0x7c/0x88 > [] el0_svc_naked+0x24/0x28 > > Fix it by check statp in __torture_print_stats(), if it is NULL, just > create a lock-torture-statistics message with zero statistic argument. It is keep to get the statistics printout at the end if with bad argument, what's your opinion about this version？ Thanks, Kefeng > > Cc: Josh Triplett > Cc: Paul E. McKenney > Signed-off-by: Kefeng Wang > --- > kernel/locking/locktorture.c | 24 ++++++++++++++---------- > 1 file changed, 14 insertions(+), 10 deletions(-) > > diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c > index 8ef1919..7f0cf9c 100644 > --- a/kernel/locking/locktorture.c > +++ b/kernel/locking/locktorture.c > @@ -647,19 +647,23 @@ static void __torture_print_stats(char *page, > bool fail = 0; > int i, n_stress; > long max = 0; > - long min = statp[0].n_lock_acquired; > + long min = 0; > long long sum = 0; > > - n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress; > - for (i = 0; i < n_stress; i++) { > - if (statp[i].n_lock_fail) > - fail = true; > - sum += statp[i].n_lock_acquired; > - if (max < statp[i].n_lock_fail) > - max = statp[i].n_lock_fail; > - if (min > statp[i].n_lock_fail) > - min = statp[i].n_lock_fail; > + if (statp) { > + min = statp[0].n_lock_acquired; > + n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress; > + for (i = 0; i < n_stress; i++) { > + if (statp[i].n_lock_fail) > + fail = true; > + sum += statp[i].n_lock_acquired; > + if (max < statp[i].n_lock_fail) > + max = statp[i].n_lock_fail; > + if (min > statp[i].n_lock_fail) > + min = statp[i].n_lock_fail; > + } > } > + > page += sprintf(page, > "%s: Total: %lld Max/Min: %ld/%ld %s Fail: %d %s\n", > write ? "Writes" : "Reads ", >