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 67880C43381 for ; Fri, 22 Mar 2019 12:20:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29F0A21900 for ; Fri, 22 Mar 2019 12:20:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553257249; bh=aAX9lWY15Bj/CWUbhU40+2+I7Ln3B3FE/jNNNWr+9sc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MqIBRFL8/6Am/rxwIb3J2t4PSa8lm5D0YeClVymubUO9JCt/BvafHR1xZ4bW7uabN SJkjNTKZvTtDG+TbJf90JPzItJllkkkMdxgNJ0HZLL/DSyoqfRaQo6IdSiJi35bxL9 Cc/tRDrKDUwdsETexNwJB+efI9aUzGavmvOdwMdc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390765AbfCVMUr (ORCPT ); Fri, 22 Mar 2019 08:20:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:59648 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390357AbfCVMUk (ORCPT ); Fri, 22 Mar 2019 08:20:40 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 D7C9721900; Fri, 22 Mar 2019 12:20:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553257239; bh=aAX9lWY15Bj/CWUbhU40+2+I7Ln3B3FE/jNNNWr+9sc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bkTLGMntzTuqzM/KFWBhwDX8kHYAO06o8TP1weifntbIOmCmFpV93CYasIVOnzxNG kxt3aECF+njo4195zZhM5QQY/c78+TBajOo0QFmaVUUv3cY/VRWzLpU/eXoA25y+Nj xwpJGlnj+X1eQYX7qqbFIyXImw/bpB1B+nmNuU+g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Rutland , Will Deacon , Catalin Marinas Subject: [PATCH 5.0 173/238] arm64: debug: Ensure debug handlers check triggering exception level Date: Fri, 22 Mar 2019 12:16:32 +0100 Message-Id: <20190322111308.489770309@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190322111258.383569278@linuxfoundation.org> References: <20190322111258.383569278@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore 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 5.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Will Deacon commit 6bd288569b50bc89fa5513031086746968f585cb upstream. Debug exception handlers may be called for exceptions generated both by user and kernel code. In many cases, this is checked explicitly, but in other cases things either happen to work by happy accident or they go slightly wrong. For example, executing 'brk #4' from userspace will enter the kprobes code and be ignored, but the instruction will be retried forever in userspace instead of delivering a SIGTRAP. Fix this issue in the most stable-friendly fashion by simply adding explicit checks of the triggering exception level to all of our debug exception handlers. Cc: Reviewed-by: Mark Rutland Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/kgdb.c | 14 ++++++++++---- arch/arm64/kernel/probes/kprobes.c | 6 ++++++ 2 files changed, 16 insertions(+), 4 deletions(-) --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -244,27 +244,33 @@ int kgdb_arch_handle_exception(int excep static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr) { + if (user_mode(regs)) + return DBG_HOOK_ERROR; + kgdb_handle_exception(1, SIGTRAP, 0, regs); - return 0; + return DBG_HOOK_HANDLED; } NOKPROBE_SYMBOL(kgdb_brk_fn) static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr) { + if (user_mode(regs)) + return DBG_HOOK_ERROR; + compiled_break = 1; kgdb_handle_exception(1, SIGTRAP, 0, regs); - return 0; + return DBG_HOOK_HANDLED; } NOKPROBE_SYMBOL(kgdb_compiled_brk_fn); static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) { - if (!kgdb_single_step) + if (user_mode(regs) || !kgdb_single_step) return DBG_HOOK_ERROR; kgdb_handle_exception(1, SIGTRAP, 0, regs); - return 0; + return DBG_HOOK_HANDLED; } NOKPROBE_SYMBOL(kgdb_step_brk_fn); --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -450,6 +450,9 @@ kprobe_single_step_handler(struct pt_reg struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); int retval; + if (user_mode(regs)) + return DBG_HOOK_ERROR; + /* return error if this is not our step */ retval = kprobe_ss_hit(kcb, instruction_pointer(regs)); @@ -466,6 +469,9 @@ kprobe_single_step_handler(struct pt_reg int __kprobes kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr) { + if (user_mode(regs)) + return DBG_HOOK_ERROR; + kprobe_handler(regs); return DBG_HOOK_HANDLED; }