From patchwork Tue Mar 5 16:45:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Schwab X-Patchwork-Id: 1051854 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=suse.de Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 44DN7K4CNWz9s4Y for ; Wed, 6 Mar 2019 03:45:49 +1100 (AEDT) Received: from localhost ([127.0.0.1]:45660 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h1DCN-0007zw-GG for incoming@patchwork.ozlabs.org; Tue, 05 Mar 2019 11:45:47 -0500 Received: from eggs.gnu.org ([209.51.188.92]:53407) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h1DBn-0007ye-Lz for qemu-devel@nongnu.org; Tue, 05 Mar 2019 11:45:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h1DBm-0003DL-Up for qemu-devel@nongnu.org; Tue, 05 Mar 2019 11:45:11 -0500 Received: from mx2.suse.de ([195.135.220.15]:36334 helo=mx1.suse.de) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h1DBk-000375-Vz for qemu-devel@nongnu.org; Tue, 05 Mar 2019 11:45:10 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A4493B796; Tue, 5 Mar 2019 16:45:06 +0000 (UTC) From: Andreas Schwab To: qemu-devel@nongnu.org X-Yow: Just imagine you're entering a state-of-the-art CAR WASH!! Date: Tue, 05 Mar 2019 17:45:05 +0100 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1.92 (gnu/linux) MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x (no timestamps) [generic] X-Received-From: 195.135.220.15 Subject: [Qemu-devel] [PATCH] linux-user: don't short-circuit read with zero length X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Riku Voipio , Laurent Vivier Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" A zero-length read still needs to do the usual checks, thus it may return errors like EBADF. This makes the read syscall emulation consistent with the pread64 syscall emulation. Signed-off-by: Andreas Schwab Reviewed-by: Laurent Vivier --- linux-user/syscall.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index ff912e89e1..7fac8e318f 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -7047,8 +7047,8 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1, _exit(arg1); return 0; /* avoid warning */ case TARGET_NR_read: - if (arg3 == 0) { - return 0; + if (arg2 == 0 && arg3 == 0) { + return get_errno(safe_read(arg1, 0, 0)); } else { if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0))) return -TARGET_EFAULT;