From nobody Thu Sep 18 23:16:07 2025 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 A1614C4332F for ; Fri, 2 Dec 2022 02:19:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232058AbiLBCTN (ORCPT ); Thu, 1 Dec 2022 21:19:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39864 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231990AbiLBCTD (ORCPT ); Thu, 1 Dec 2022 21:19:03 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2A35D678D for ; Thu, 1 Dec 2022 18:18:59 -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 ams.source.kernel.org (Postfix) with ESMTPS id 766BAB82032 for ; Fri, 2 Dec 2022 02:18:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25870C433C1; Fri, 2 Dec 2022 02:18:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669947537; bh=R9kOaJyETkU6/vr64DTuIeuT6pjd+1zjqb/XRu6SYXI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q/+XSbpX8LbQtmkoSF88IcMiq2vXBlzkel817bNeZn1zXpn0qv5C1HcJVyzkk0n0W ScAB6ot6ZIaTErzIXVnd/zJSEpkNuzuzQ33nT11zATwVO+hjZuNrzkkjjVOKMzwMgH znjNoUF947eQLb9W8c3WYzleXKkasbaQDjHWABqQI+198sqdvRnPsUoQGssdIGesyA 538c4h8iPppXIj3oQvX58WgYFlFBgjnUHkBVegYVT8yTBU6pqkLnL/klRKr3+mDpzo qdNiH4sChPThlNmk+MQ0EdoLepgkFQkygqV2rM3UphEfoK5E4Ohny9O6nB9qDtvEJ9 0+lP9HJZec2YA== From: "Masami Hiramatsu (Google)" To: Catalin Marinas , Will Deacon Cc: Mark Rutland , Mark Brown , Kalesh Singh , Masami Hiramatsu , Marc Zyngier , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sandeepa Prabhu Subject: [PATCH v2 3/3] arm64: kprobes: Return DBG_HOOK_ERROR if kprobes can not handle a BRK Date: Fri, 2 Dec 2022 11:18:52 +0900 Message-Id: <166994753273.439920.6629626290560350760.stgit@devnote3> X-Mailer: git-send-email 2.39.0.rc0.267.gcb52ba06e7-goog In-Reply-To: <166994750386.439920.1754385804350980158.stgit@devnote3> References: <166994750386.439920.1754385804350980158.stgit@devnote3> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu (Google) Return DBG_HOOK_ERROR if kprobes can not handle a BRK because it fails to find a kprobe corresponding to the address. Since arm64 kprobes uses stop_machine based text patching for removing BRK, it ensures all running kprobe_break_handler() is done at that point. And after removing the BRK, it removes the kprobe from its hash list. Thus, if the kprobe_break_handler() fails to find kprobe from hash list, there is a bug. Signed-off-by: Masami Hiramatsu (Google) Acked-by: Mark Rutland --- Changes in v2: - Update comments in the code. --- arch/arm64/kernel/probes/kprobes.c | 78 +++++++++++++++++---------------= ---- 1 file changed, 36 insertions(+), 42 deletions(-) diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/= kprobes.c index d2ae37f89774..f35d059a9a36 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -298,7 +298,8 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs= , unsigned int fsr) return 0; } =20 -static void __kprobes kprobe_handler(struct pt_regs *regs) +static int __kprobes +kprobe_breakpoint_handler(struct pt_regs *regs, unsigned long esr) { struct kprobe *p, *cur_kprobe; struct kprobe_ctlblk *kcb; @@ -308,39 +309,44 @@ static void __kprobes kprobe_handler(struct pt_regs *= regs) cur_kprobe =3D kprobe_running(); =20 p =3D get_kprobe((kprobe_opcode_t *) addr); + if (WARN_ON_ONCE(!p)) { + /* + * Something went wrong. This BRK used an immediate reserved + * for kprobes, but we couldn't find any corresponding probe. + */ + return DBG_HOOK_ERROR; + } =20 - if (p) { - if (cur_kprobe) { - if (reenter_kprobe(p, regs, kcb)) - return; - } else { - /* Probe hit */ - set_current_kprobe(p); - kcb->kprobe_status =3D KPROBE_HIT_ACTIVE; - - /* - * If we have no pre-handler or it returned 0, we - * continue with normal processing. If we have a - * pre-handler and it returned non-zero, it will - * modify the execution path and no need to single - * stepping. Let's just reset current kprobe and exit. - */ - if (!p->pre_handler || !p->pre_handler(p, regs)) { - setup_singlestep(p, regs, kcb, 0); - } else - reset_current_kprobe(); - } + if (cur_kprobe) { + /* Hit a kprobe inside another kprobe */ + if (!reenter_kprobe(p, regs, kcb)) + return DBG_HOOK_ERROR; + } else { + /* Probe hit */ + set_current_kprobe(p); + kcb->kprobe_status =3D KPROBE_HIT_ACTIVE; + + /* + * If we have no pre-handler or it returned 0, we + * continue with normal processing. If we have a + * pre-handler and it returned non-zero, it will + * modify the execution path and not need to single-step + * Let's just reset current kprobe and exit. + */ + if (!p->pre_handler || !p->pre_handler(p, regs)) + setup_singlestep(p, regs, kcb, 0); + else + reset_current_kprobe(); } - /* - * The breakpoint instruction was removed right - * after we hit it. Another cpu has removed - * either a probepoint or a debugger breakpoint - * at this address. In either case, no further - * handling of this interrupt is appropriate. - * Return back to original instruction, and continue. - */ + + return DBG_HOOK_HANDLED; } =20 +static struct break_hook kprobes_break_hook =3D { + .imm =3D KPROBES_BRK_IMM, + .fn =3D kprobe_breakpoint_handler, +}; + static int __kprobes kprobe_breakpoint_ss_handler(struct pt_regs *regs, unsigned long esr) { @@ -365,18 +371,6 @@ static struct break_hook kprobes_break_ss_hook =3D { .fn =3D kprobe_breakpoint_ss_handler, }; =20 -static int __kprobes -kprobe_breakpoint_handler(struct pt_regs *regs, unsigned long esr) -{ - kprobe_handler(regs); - return DBG_HOOK_HANDLED; -} - -static struct break_hook kprobes_break_hook =3D { - .imm =3D KPROBES_BRK_IMM, - .fn =3D kprobe_breakpoint_handler, -}; - /* * Provide a blacklist of symbols identifying ranges which cannot be kprob= ed. * This blacklist is exposed to userspace via debugfs (kprobes/blacklist).