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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 D5C4CC10F11 for ; Wed, 24 Apr 2019 17:37:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A3A4A21903 for ; Wed, 24 Apr 2019 17:37:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556127440; bh=SXN5ALCi7pHmuheWQdGmIOtPGRWc5TDENC2iqp2pl+c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=psNgHd1xOIZuXOvnK9VKTfsAFNWXpQ4xn1CN9eaGRSDa1zCz8Gj5tl0d/6+LB5mGi bS7uZ0+x9LYC+Evcn7JGzmV9ak0FaHiXfDKKfn7rKFVEzPQRpWEbmHe2MGhzkKHRqw Q1DV1ga72cOpM3MB2+bAwauHIiCAmqPTLJ8WxUlA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392062AbfDXRhT (ORCPT ); Wed, 24 Apr 2019 13:37:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:36108 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403957AbfDXRhN (ORCPT ); Wed, 24 Apr 2019 13:37:13 -0400 Received: from localhost (62-193-50-229.as16211.net [62.193.50.229]) (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 6992A21904; Wed, 24 Apr 2019 17:37:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556127432; bh=SXN5ALCi7pHmuheWQdGmIOtPGRWc5TDENC2iqp2pl+c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=alGDKeyvNyYFLopLSgGrVLaU03KSCerNX0xCjbgcNv5/OoYoE2DNtvf0EH4iIr/c6 2QkdZH3S8pak9H2rMVNtqwcldSJecGtpDE9MAPk/y3NYcLF6KEfEGQTI7tWzAlFywy 5M35B9B34nb53/v7/nGG4nCX++zYsEwAkPHS/2X0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrea Righi , Masami Hiramatsu , Steven Rostedt , Linus Torvalds , Mathieu Desnoyers , Peter Zijlstra , Thomas Gleixner , Ingo Molnar Subject: [PATCH 5.0 089/115] x86/kprobes: Avoid kretprobe recursion bug Date: Wed, 24 Apr 2019 19:10:25 +0200 Message-Id: <20190424170930.080148720@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190424170924.797924502@linuxfoundation.org> References: <20190424170924.797924502@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu commit b191fa96ea6dc00d331dcc28c1f7db5e075693a0 upstream. Avoid kretprobe recursion loop bg by setting a dummy kprobes to current_kprobe per-CPU variable. This bug has been introduced with the asm-coded trampoline code, since previously it used another kprobe for hooking the function return placeholder (which only has a nop) and trampoline handler was called from that kprobe. This revives the old lost kprobe again. With this fix, we don't see deadlock anymore. And you can see that all inner-called kretprobe are skipped. event_1 235 0 event_2 19375 19612 The 1st column is recorded count and the 2nd is missed count. Above shows (event_1 rec) + (event_2 rec) ~= (event_2 missed) (some difference are here because the counter is racy) Reported-by: Andrea Righi Tested-by: Andrea Righi Signed-off-by: Masami Hiramatsu Acked-by: Steven Rostedt Cc: Linus Torvalds Cc: Mathieu Desnoyers Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: stable@vger.kernel.org Fixes: c9becf58d935 ("[PATCH] kretprobe: kretprobe-booster") Link: http://lkml.kernel.org/r/155094064889.6137.972160690963039.stgit@devbox Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/kprobes/core.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -749,11 +749,16 @@ asm( NOKPROBE_SYMBOL(kretprobe_trampoline); STACK_FRAME_NON_STANDARD(kretprobe_trampoline); +static struct kprobe kretprobe_kprobe = { + .addr = (void *)kretprobe_trampoline, +}; + /* * Called from kretprobe_trampoline */ static __used void *trampoline_handler(struct pt_regs *regs) { + struct kprobe_ctlblk *kcb; struct kretprobe_instance *ri = NULL; struct hlist_head *head, empty_rp; struct hlist_node *tmp; @@ -763,6 +768,17 @@ static __used void *trampoline_handler(s void *frame_pointer; bool skipped = false; + preempt_disable(); + + /* + * Set a dummy kprobe for avoiding kretprobe recursion. + * Since kretprobe never run in kprobe handler, kprobe must not + * be running at this point. + */ + kcb = get_kprobe_ctlblk(); + __this_cpu_write(current_kprobe, &kretprobe_kprobe); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + INIT_HLIST_HEAD(&empty_rp); kretprobe_hash_lock(current, &head, &flags); /* fixup registers */ @@ -838,10 +854,9 @@ static __used void *trampoline_handler(s orig_ret_address = (unsigned long)ri->ret_addr; if (ri->rp && ri->rp->handler) { __this_cpu_write(current_kprobe, &ri->rp->kp); - get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; ri->ret_addr = correct_ret_addr; ri->rp->handler(ri, regs); - __this_cpu_write(current_kprobe, NULL); + __this_cpu_write(current_kprobe, &kretprobe_kprobe); } recycle_rp_inst(ri, &empty_rp); @@ -857,6 +872,9 @@ static __used void *trampoline_handler(s kretprobe_hash_unlock(current, &flags); + __this_cpu_write(current_kprobe, NULL); + preempt_enable(); + hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { hlist_del(&ri->hlist); kfree(ri);