From nobody Sun Nov 9 16:25:24 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 155180440121675.58917647983753; Tue, 5 Mar 2019 08:46:41 -0800 (PST) Received: from localhost ([127.0.0.1]:45667 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h1DD6-0000Fr-6U for importer@patchew.org; Tue, 05 Mar 2019 11:46:32 -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 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) X-Virus-Scanned: by amavisd-new at test-mx.suse.de 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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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, a= bi_long arg1, _exit(arg1); return 0; /* avoid warning */ case TARGET_NR_read: - if (arg3 =3D=3D 0) { - return 0; + if (arg2 =3D=3D 0 && arg3 =3D=3D 0) { + return get_errno(safe_read(arg1, 0, 0)); } else { if (!(p =3D lock_user(VERIFY_WRITE, arg2, arg3, 0))) return -TARGET_EFAULT; --=20 2.21.0 --=20 Andreas Schwab, SUSE Labs, schwab@suse.de GPG Key fingerprint =3D 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."