From patchwork Fri Jan 30 12:59:48 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kirill Batuzov X-Patchwork-Id: 434848 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 2A30A1402AE for ; Sat, 31 Jan 2015 00:00:22 +1100 (AEDT) Received: from localhost ([::1]:36512 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHBBM-0005pY-RO for incoming@patchwork.ozlabs.org; Fri, 30 Jan 2015 08:00:20 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55575) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHBB1-0005Pu-4l for qemu-devel@nongnu.org; Fri, 30 Jan 2015 07:59:59 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YHBAx-000734-Tk for qemu-devel@nongnu.org; Fri, 30 Jan 2015 07:59:59 -0500 Received: from smtp.ispras.ru ([83.149.199.79]:33559) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHBAx-000730-MP for qemu-devel@nongnu.org; Fri, 30 Jan 2015 07:59:55 -0500 Received: from bulbul.intra.ispras.ru (unknown [83.149.199.91]) by smtp.ispras.ru (Postfix) with ESMTP id 841FA21EFA; Fri, 30 Jan 2015 15:59:54 +0300 (MSK) From: Kirill Batuzov To: qemu-devel@nongnu.org Date: Fri, 30 Jan 2015 15:59:48 +0300 Message-Id: <1422622788-29375-1-git-send-email-batuzovk@ispras.ru> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: References: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 83.149.199.79 Cc: Peter Maydell , Kirill Batuzov Subject: [Qemu-devel] [PATCH v2] target-arm: check that LSB <= MSB in BFI instruction X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org The documentation states that if LSB > MSB in BFI instruction behaviour is unpredictable. Currently QEMU crashes because of assertion failure in this case: tcg/tcg-op.h:2061: tcg_gen_deposit_i32: Assertion `len <= 32' failed. While assertion failure may meet the "unpredictable" definition this behaviour is undesirable because it allows an unprivileged guest program to crash the emulator with the OS and other programs. This patch addresses the issue by throwing illegal instruction exception if LSB > MSB. Only ARM decoder is affected because Thumb decoder already has this check in place. To reproduce issue run the following program int main(void) { asm volatile (".long 0x07c00c12" :: ); return 0; } compiled with gcc -marm -static badop_arm.c -o badop_arm Signed-off-by: Kirill Batuzov --- target-arm/translate.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/target-arm/translate.c b/target-arm/translate.c index bdfcdf1..2c1c2a7 100644 --- a/target-arm/translate.c +++ b/target-arm/translate.c @@ -8739,6 +8739,10 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn) ARCH(6T2); shift = (insn >> 7) & 0x1f; i = (insn >> 16) & 0x1f; + if (i < shift) { + /* UNPREDICTABLE; we choose to UNDEF */ + goto illegal_op; + } i = i + 1 - shift; if (rm == 15) { tmp = tcg_temp_new_i32();