From patchwork Mon May 3 17:36:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Madhavan T. Venkataraman" X-Patchwork-Id: 12236625 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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 5C7CEC433ED for ; Mon, 3 May 2021 17:38:25 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BC5E8610E9 for ; Mon, 3 May 2021 17:38:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BC5E8610E9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Cc:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=WPjpVc6UzCjrI5qtPm7GUhYlWB4SJLyQpS2Jmv4d8QY=; b=VLAoSDOkVqk7QhjtpPif1QgaG HSbvufzBabk3D8cq/de6sRNI9oTOSIU/RhRNCA8GA2VCYSupCiMkZnlp5EZZAsaD3Yg6RCyy0JbjP isByDFVLDA/YzBQ6bgJbW3/8Js0nXcVOdHLJUthDWjApqeMgoMFSpm62Vhxr+zVRLz2XjbyInSphs Uv3IvMpihuhI0Pny4ZNvrYXlJwCYcxBkAj3y0XCrcy6XU/2OUtQHQhaTSzYPHsav3RSVO9QeCgt0c ukDKspuhMxLrIPHX6LZPxdHcV8+l702Fg965K1e837cXmojecpS83IrsQJTuXLsor0oxgohjJiJQh eYX97HYgA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1ldcUk-00EWSQ-6n; Mon, 03 May 2021 17:36:34 +0000 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1ldcUg-00EWRy-11 for linux-arm-kernel@desiato.infradead.org; Mon, 03 May 2021 17:36:30 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:To:From:Sender: Reply-To:Cc:Content-Type:Content-ID:Content-Description; bh=27H+BvFer3s1Y37vngYKoBI/y9wscqHm39MmyAoxw0U=; b=zHu+rOAeqpcYjvXC9k3YL72bnw x0c+MWwiUuWpWVWEN3W/oklzKUVRN9pROEjbUcOmk68rKwmFgwVsxBkNxrBxnuheuZhVv6gmWR+/d 5Eisa6aIcvuKREfZeVOXQE/3JiBX3Y8sEPEP68diauoU8KALLZefgMrjQOSnCPHvHo7gxqbITscG7 8jLRM/V4CIenUA0F4AQP0644pISnR3PnNKLHQy+dmE3430FBKq8PfP+t7Ekf6sSUJaK0tirj2Ecde sAltuGhQMiF7E0JL1hodDzm+LM13tdLGoJzHywJXz33vJir1adhBicAazTsBf1D9XyAerXjDnt1HQ DHL97YLg==; Received: from linux.microsoft.com ([13.77.154.182]) by bombadil.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1ldcUd-003MIX-2C for linux-arm-kernel@lists.infradead.org; Mon, 03 May 2021 17:36:28 +0000 Received: from x64host.home (unknown [47.187.223.33]) by linux.microsoft.com (Postfix) with ESMTPSA id F400B20B8006; Mon, 3 May 2021 10:36:23 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com F400B20B8006 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1620063384; bh=27H+BvFer3s1Y37vngYKoBI/y9wscqHm39MmyAoxw0U=; h=From:To:Subject:Date:In-Reply-To:References:From; b=dl6V/Uswvh85+qjvxPyvO12cWqKGTHC7p2cooPOwG26LmWMxATKi/fYBN53tScEXR 1mhyM3FpBIYEpnthksh7zyag6o50NOTInqXXOS+BFbhMwN40GRdJA/denkOBcnikNf WGxKCP2a75rmSDeUb6UPt6EdYGgAM7nKWerpV8pc= From: madvenka@linux.microsoft.com To: broonie@kernel.org, jpoimboe@redhat.com, mark.rutland@arm.com, jthierry@redhat.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, pasha.tatashin@soleen.com, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com Subject: [RFC PATCH v3 1/4] arm64: Introduce stack trace reliability checks in the unwinder Date: Mon, 3 May 2021 12:36:12 -0500 Message-Id: <20210503173615.21576-2-madvenka@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210503173615.21576-1-madvenka@linux.microsoft.com> References: <65cf4dfbc439b010b50a0c46ec500432acde86d6> <20210503173615.21576-1-madvenka@linux.microsoft.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210503_103627_177729_4EDFC29A X-CRM114-Status: GOOD ( 16.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: "Madhavan T. Venkataraman" The unwinder should check for the presence of various features and conditions that can render the stack trace unreliable and mark the the stack trace as unreliable for the benefit of the caller. Introduce the first reliability check - If a return PC encountered in a stack trace is not a valid kernel text address, the stack trace is considered unreliable. It could be some generated code. Mark the stack trace unreliable. Other reliability checks will be added in the future. Signed-off-by: Madhavan T. Venkataraman --- arch/arm64/include/asm/stacktrace.h | 4 ++++ arch/arm64/kernel/stacktrace.c | 19 ++++++++++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h index eb29b1fe8255..f1eab6b029f7 100644 --- a/arch/arm64/include/asm/stacktrace.h +++ b/arch/arm64/include/asm/stacktrace.h @@ -49,6 +49,8 @@ struct stack_info { * * @graph: When FUNCTION_GRAPH_TRACER is selected, holds the index of a * replacement lr value in the ftrace graph stack. + * + * @reliable: Is this stack frame reliable? */ struct stackframe { unsigned long fp; @@ -59,6 +61,7 @@ struct stackframe { #ifdef CONFIG_FUNCTION_GRAPH_TRACER int graph; #endif + bool reliable; }; extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame); @@ -169,6 +172,7 @@ static inline void start_backtrace(struct stackframe *frame, bitmap_zero(frame->stacks_done, __NR_STACK_TYPES); frame->prev_fp = 0; frame->prev_type = STACK_TYPE_UNKNOWN; + frame->reliable = true; } #endif /* __ASM_STACKTRACE_H */ diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index d55bdfb7789c..c21a1bca28f3 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -44,6 +44,8 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) unsigned long fp = frame->fp; struct stack_info info; + frame->reliable = true; + /* Terminal record; nothing to unwind */ if (!fp) return -ENOENT; @@ -86,12 +88,24 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) */ frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); + frame->pc = ptrauth_strip_insn_pac(frame->pc); frame->prev_fp = fp; frame->prev_type = info.type; + /* + * First, make sure that the return address is a proper kernel text + * address. A NULL or invalid return address probably means there's + * some generated code which __kernel_text_address() doesn't know + * about. Mark the stack trace as not reliable. + */ + if (!__kernel_text_address(frame->pc)) { + frame->reliable = false; + return 0; + } + #ifdef CONFIG_FUNCTION_GRAPH_TRACER if (tsk->ret_stack && - (ptrauth_strip_insn_pac(frame->pc) == (unsigned long)return_to_handler)) { + frame->pc == (unsigned long)return_to_handler) { struct ftrace_ret_stack *ret_stack; /* * This is a case where function graph tracer has @@ -103,11 +117,10 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) if (WARN_ON_ONCE(!ret_stack)) return -EINVAL; frame->pc = ret_stack->ret; + frame->pc = ptrauth_strip_insn_pac(frame->pc); } #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ - frame->pc = ptrauth_strip_insn_pac(frame->pc); - return 0; } NOKPROBE_SYMBOL(unwind_frame);