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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AB8B0C433F5 for ; Mon, 15 Nov 2021 08:50:34 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 7395763219 for ; Mon, 15 Nov 2021 08:50:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 7395763219 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; 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:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=snp1/uP4pcDvNN0n5PAVuEdyKX8x6GvPQzSsXdJYskg=; b=IwY0oTwyJCgaXT /rUTy2lZBa3Z4To+TxNkksscuTGhElIREzsXCv0fr7YwMXdfPkRZALwNT7EFtT5pG8c1Zg9Pm8Rcj RhUwuCaQToMcGASHSMfCls9Uoz1jrSqQNlUKpWobbrejcLHMWy7l7IDYyAdF4MlDs0FXPIXdtbFWi fugt5rUNSWOuXFHForiib4OfYa7hNzTpCNHuLAcVpGTEKs3bdQSnFbQI8q+v4UB9MJQiRMmbw8o+d 7nNCpUmsJ3e8SJhQULAxYG61c58jgBtK2CgLt7USR1bq/F50slRiyz//kze6pFQ/QkkwWtBEBTOem lMIOWNKA1weCzkxZN1vg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mmXfq-00EjcF-M4; Mon, 15 Nov 2021 08:49:11 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mmXec-00Ej7g-Kw for linux-arm-kernel@lists.infradead.org; Mon, 15 Nov 2021 08:47:56 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5CB7760273; Mon, 15 Nov 2021 08:47:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1636966074; bh=GnYP4XD3bbYKhfaUkEvMW0AAOMBXMBt8P0u5VZWAovg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ml39W6wmB+MIn/3KJ+DDvyuop2Kdn51uI7pChrP6jvQzn9h9PLNqPxhUlOeO7njUh jnHLK8jKrd/D3Ux0cbQRlwGUmN6XQaMgTb0ZMwb2+9Moj+0H6X+9c8ZsjIHBgrZXDE /nVpU8dP2TiyIq70xYyKwkM/8+JYgV4Tj/xEy6ELoq7W0ANbuKi9X1xwwpfYr3Wc5g Kt3KqH2a/2GuTJKSoBQGuKUqjxrbrJ6tpxVi2x/Eoa4XOOsobmlqIZnAwc8Gvng/eT 9yzZTf2texnduJP0Fl/uYqlFxfDQJ7/d73rXfvm/hFLAwm7jDaBEaB5zP68++YHUVC v5jMJdrGFAOig== From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Russell King , Arnd Bergmann , Kees Cook , Keith Packard , Linus Walleij , Nick Desaulniers , Nicolas Pitre Subject: [PATCH v4 6/9] ARM: backtrace-clang: avoid crash on bogus frame pointer Date: Mon, 15 Nov 2021 09:47:29 +0100 Message-Id: <20211115084732.3704393-7-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211115084732.3704393-1-ardb@kernel.org> References: <20211115084732.3704393-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1739; h=from:subject; bh=GnYP4XD3bbYKhfaUkEvMW0AAOMBXMBt8P0u5VZWAovg=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBhkh6e+5CiZeedH81UXGGkY0gi9EKeV1hbG/4cjZVl OgdDdPCJAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCYZIengAKCRDDTyI5ktmPJJH/C/ 9FNndmvFSh0DNSKvOQ0szX63wDTLBuGjQE6+C3MMnmfhuZ3LELugfdW94awzHZQfGsYwX/FmS8z/aM GNF9DhOVafyKq1sciSk3ZCGO/nloKSkai5Xo0x6YO2wmG7ixu92szqpRjDNeECehXWjxMRzfMPOgcL FT7alsEVAAI1l1L1OA7A3omDUE/WFsPfrWPe114FXjhXt3AL1biEfVYrphuwR3EivGw5G0Fk2jaODY 35AwH9nIICaannPafeLCOzXWFIIuHHHHxfhLWkB2hEcUHetIEkJZ7+R5ckCYH7sp46MFOwVJtQgHWa I4awcWS4EQuuwIYtwM8N/W0OfhskOEa1XC/rjl34yicLsL1iSZ0WstZivuLTKMzbNHhmBIL9RE9gCS EfL0rI/fITE6uL323ADCzaQBBCReZsdHBInXCxR77bPuoC7tkMXNKJ1RWiquwXqQhxw0Wmq8PTqksM OUby73PkDpClkGfo9za520Tg7o5+mFq18SxSMqU93AiFs= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211115_004754_744842_A7216D12 X-CRM114-Status: GOOD ( 14.11 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The Clang backtrace code dereferences the link register value pulled from the stack to decide whether the caller was a branch-and-link instruction, in order to subsequently decode the offset to find the start of the calling function. Unlike other loads in this routine, this one is not protected by a fixup, and may therefore cause a crash if the address in question is bogus. So let's fix this, by treating the fault as a failure to decode the 'bl' instruction. To avoid a label renum, reuse a fixup label that guards an instruction that cannot fault to begin with. Signed-off-by: Ard Biesheuvel Reviewed-by: Nick Desaulniers --- arch/arm/lib/backtrace-clang.S | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm/lib/backtrace-clang.S b/arch/arm/lib/backtrace-clang.S index 5b2cdb1003e3..5b4bca85d06d 100644 --- a/arch/arm/lib/backtrace-clang.S +++ b/arch/arm/lib/backtrace-clang.S @@ -144,7 +144,7 @@ for_each_frame: tst frame, mask @ Check for address exceptions */ 1003: ldr sv_lr, [sv_fp, #4] @ get saved lr from next frame - ldr r0, [sv_lr, #-4] @ get call instruction +1004: ldr r0, [sv_lr, #-4] @ get call instruction ldr r3, .Lopcode+4 and r2, r3, r0 @ is this a bl call teq r2, r3 @@ -164,7 +164,7 @@ finished_setup: /* * Print the function (sv_pc) and where it was called from (sv_lr). */ -1004: mov r0, sv_pc + mov r0, sv_pc mov r1, sv_lr mov r2, frame @@ -210,7 +210,7 @@ ENDPROC(c_backtrace) .long 1001b, 1006b .long 1002b, 1006b .long 1003b, 1006b - .long 1004b, 1006b + .long 1004b, finished_setup .long 1005b, 1006b .popsection -- 2.30.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel