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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 7FDA6C31E4B for ; Fri, 14 Jun 2019 21:40:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EE67217F9 for ; Fri, 14 Jun 2019 21:40:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726264AbfFNVkH (ORCPT ); Fri, 14 Jun 2019 17:40:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:39150 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725809AbfFNVkG (ORCPT ); Fri, 14 Jun 2019 17:40:06 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7BB53217F9; Fri, 14 Jun 2019 21:40:05 +0000 (UTC) Date: Fri, 14 Jun 2019 17:40:04 -0400 From: Steven Rostedt To: Wei Li Cc: , , Subject: Re: [PATCH] ftrace: fix NULL pointer dereference in free_ftrace_func_mapper() Message-ID: <20190614174004.1e2efef4@gandalf.local.home> In-Reply-To: <20190606031754.10798-1-liwei391@huawei.com> References: <20190606031754.10798-1-liwei391@huawei.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 6 Jun 2019 11:17:54 +0800 Wei Li wrote: > The mapper may be NULL when called from register_ftrace_function_probe() > with probe->data == NULL. > > This issue can be reproduced as follow (it may be coverd by compiler > optimization sometime): > > / # cat /sys/kernel/debug/tracing/set_ftrace_filter I'm not able to reproduce this, but I have nothing against the patch. It seems like a sane test. We can probably remove all the: if (!mapper) return; before callers of this function then. I'll apply this for my next push to Linus. -- Steve > #### all functions enabled #### > / # echo foo_bar:dump > /sys/kernel/debug/tracing/set_ftrace_filter > [ 206.949100] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 > [ 206.952402] Mem abort info: > [ 206.952819] ESR = 0x96000006 > [ 206.955326] Exception class = DABT (current EL), IL = 32 bits > [ 206.955844] SET = 0, FnV = 0 > [ 206.956272] EA = 0, S1PTW = 0 > [ 206.956652] Data abort info: > [ 206.957320] ISV = 0, ISS = 0x00000006 > [ 206.959271] CM = 0, WnR = 0 > [ 206.959938] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000419f3a000 > [ 206.960483] [0000000000000000] pgd=0000000411a87003, pud=0000000411a83003, pmd=0000000000000000 > [ 206.964953] Internal error: Oops: 96000006 [#1] SMP > [ 206.971122] Dumping ftrace buffer: > [ 206.973677] (ftrace buffer empty) > [ 206.975258] Modules linked in: > [ 206.976631] Process sh (pid: 281, stack limit = 0x(____ptrval____)) > [ 206.978449] CPU: 10 PID: 281 Comm: sh Not tainted 5.2.0-rc1+ #17 > [ 206.978955] Hardware name: linux,dummy-virt (DT) > [ 206.979883] pstate: 60000005 (nZCv daif -PAN -UAO) > [ 206.980499] pc : free_ftrace_func_mapper+0x2c/0x118 > [ 206.980874] lr : ftrace_count_free+0x68/0x80 > [ 206.982539] sp : ffff0000182f3ab0 > [ 206.983102] x29: ffff0000182f3ab0 x28: ffff8003d0ec1700 > [ 206.983632] x27: ffff000013054b40 x26: 0000000000000001 > [ 206.984000] x25: ffff00001385f000 x24: 0000000000000000 > [ 206.984394] x23: ffff000013453000 x22: ffff000013054000 > [ 206.984775] x21: 0000000000000000 x20: ffff00001385fe28 > [ 206.986575] x19: ffff000013872c30 x18: 0000000000000000 > [ 206.987111] x17: 0000000000000000 x16: 0000000000000000 > [ 206.987491] x15: ffffffffffffffb0 x14: 0000000000000000 > [ 206.987850] x13: 000000000017430e x12: 0000000000000580 > [ 206.988251] x11: 0000000000000000 x10: cccccccccccccccc > [ 206.988740] x9 : 0000000000000000 x8 : ffff000013917550 > [ 206.990198] x7 : ffff000012fac2e8 x6 : ffff000012fac000 > [ 206.991008] x5 : ffff0000103da588 x4 : 0000000000000001 > [ 206.991395] x3 : 0000000000000001 x2 : ffff000013872a28 > [ 206.991771] x1 : 0000000000000000 x0 : 0000000000000000 > [ 206.992557] Call trace: > [ 206.993101] free_ftrace_func_mapper+0x2c/0x118 > [ 206.994827] ftrace_count_free+0x68/0x80 > [ 206.995238] release_probe+0xfc/0x1d0 > [ 206.995555] register_ftrace_function_probe+0x4a8/0x868 > [ 206.995923] ftrace_trace_probe_callback.isra.4+0xb8/0x180 > [ 206.996330] ftrace_dump_callback+0x50/0x70 > [ 206.996663] ftrace_regex_write.isra.29+0x290/0x3a8 > [ 206.997157] ftrace_filter_write+0x44/0x60 > [ 206.998971] __vfs_write+0x64/0xf0 > [ 206.999285] vfs_write+0x14c/0x2f0 > [ 206.999591] ksys_write+0xbc/0x1b0 > [ 206.999888] __arm64_sys_write+0x3c/0x58 > [ 207.000246] el0_svc_common.constprop.0+0x408/0x5f0 > [ 207.000607] el0_svc_handler+0x144/0x1c8 > [ 207.000916] el0_svc+0x8/0xc > [ 207.003699] Code: aa0003f8 a9025bf5 aa0103f5 f946ea80 (f9400303) > [ 207.008388] ---[ end trace 7b6d11b5f542bdf1 ]--- > [ 207.010126] Kernel panic - not syncing: Fatal exception > [ 207.011322] SMP: stopping secondary CPUs > [ 207.013956] Dumping ftrace buffer: > [ 207.014595] (ftrace buffer empty) > [ 207.015632] Kernel Offset: disabled > [ 207.017187] CPU features: 0x002,20006008 > [ 207.017985] Memory Limit: none > [ 207.019825] ---[ end Kernel panic - not syncing: Fatal exception ]--- > > Signed-off-by: Wei Li > --- > kernel/trace/ftrace.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index a12aff849c04..7e2488da69ac 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -4221,10 +4221,13 @@ void free_ftrace_func_mapper(struct ftrace_func_mapper *mapper, > struct ftrace_func_entry *entry; > struct ftrace_func_map *map; > struct hlist_head *hhd; > - int size = 1 << mapper->hash.size_bits; > - int i; > + int size, i; > + > + if (!mapper) > + return; > > if (free_func && mapper->hash.count) { > + size = 1 << mapper->hash.size_bits; > for (i = 0; i < size; i++) { > hhd = &mapper->hash.buckets[i]; > hlist_for_each_entry(entry, hhd, hlist) {