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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5EEFC4332F for ; Sun, 20 Nov 2022 20:13:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229695AbiKTUMe (ORCPT ); Sun, 20 Nov 2022 15:12:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229518AbiKTUM3 (ORCPT ); Sun, 20 Nov 2022 15:12:29 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8CC3027D for ; Sun, 20 Nov 2022 12:12:25 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 25D4B60D29 for ; Sun, 20 Nov 2022 20:12:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B5C9C4314A; Sun, 20 Nov 2022 20:12:23 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1owqfu-00DiY3-1z; Sun, 20 Nov 2022 15:12:22 -0500 Message-ID: <20221120201222.492058544@goodmis.org> User-Agent: quilt/0.66 Date: Sun, 20 Nov 2022 15:12:01 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , Zhao Gongyi , Li Huafei Subject: [for-linus][PATCH 5/7] kprobes: Skip clearing aggrprobes post_handler in kprobe-on-ftrace case References: <20221120201156.868430827@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Li Huafei In __unregister_kprobe_top(), if the currently unregistered probe has post_handler but other child probes of the aggrprobe do not have post_handler, the post_handler of the aggrprobe is cleared. If this is a ftrace-based probe, there is a problem. In later calls to disarm_kprobe(), we will use kprobe_ftrace_ops because post_handler is NULL. But we're armed with kprobe_ipmodify_ops. This triggers a WARN in __disarm_kprobe_ftrace() and may even cause use-after-free: Failed to disarm kprobe-ftrace at kernel_clone+0x0/0x3c0 (error -2) WARNING: CPU: 5 PID: 137 at kernel/kprobes.c:1135 __disarm_kprobe_ftrace.isra.21+0xcf/0xe0 Modules linked in: testKprobe_007(-) CPU: 5 PID: 137 Comm: rmmod Not tainted 6.1.0-rc4-dirty #18 [...] Call Trace: __disable_kprobe+0xcd/0xe0 __unregister_kprobe_top+0x12/0x150 ? mutex_lock+0xe/0x30 unregister_kprobes.part.23+0x31/0xa0 unregister_kprobe+0x32/0x40 __x64_sys_delete_module+0x15e/0x260 ? do_user_addr_fault+0x2cd/0x6b0 do_syscall_64+0x3a/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] For the kprobe-on-ftrace case, we keep the post_handler setting to identify this aggrprobe armed with kprobe_ipmodify_ops. This way we can disarm it correctly. Link: https://lore.kernel.org/all/20221112070000.35299-1-lihuafei1@huawei.com/ Fixes: 0bc11ed5ab60 ("kprobes: Allow kprobes coexist with livepatch") Reported-by: Zhao Gongyi Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Li Huafei Acked-by: Masami Hiramatsu (Google) Signed-off-by: Masami Hiramatsu (Google) --- kernel/kprobes.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index cd9f5a66a690..3050631e528d 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1766,7 +1766,13 @@ static int __unregister_kprobe_top(struct kprobe *p) if ((list_p != p) && (list_p->post_handler)) goto noclean; } - ap->post_handler = NULL; + /* + * For the kprobe-on-ftrace case, we keep the + * post_handler setting to identify this aggrprobe + * armed with kprobe_ipmodify_ops. + */ + if (!kprobe_ftrace(ap)) + ap->post_handler = NULL; } noclean: /* -- 2.35.1