From nobody Wed Feb 11 00:59:48 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.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 1763784738990140.44450761697954; Fri, 21 Nov 2025 20:12:18 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vMd2Z-0001VC-Df; Fri, 21 Nov 2025 21:07:56 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vMcJF-00034B-2c; Fri, 21 Nov 2025 20:21:05 -0500 Received: from isrv.corpit.ru ([212.248.84.144]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vMcHC-0006d7-IK; Fri, 21 Nov 2025 20:21:00 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id F01B216CA4F; Fri, 21 Nov 2025 21:44:22 +0300 (MSK) Received: from think4mjt.tls.msk.ru (mjtthink.wg.tls.msk.ru [192.168.177.146]) by tsrv.corpit.ru (Postfix) with ESMTP id 77E6A321C8B; Fri, 21 Nov 2025 21:44:31 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Mark Cave-Ayland , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Paolo Bonzini , Michael Tokarev Subject: [Stable-10.0.7 20/81] esp.c: fix esp_cdb_ready() FIFO wraparound limit calculation Date: Fri, 21 Nov 2025 21:43:19 +0300 Message-ID: <20251121184424.1137669-20-mjt@tls.msk.ru> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.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; Received-SPF: pass client-ip=212.248.84.144; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1763784741548018900 From: Mark Cave-Ayland The original calculation in commit 3cc70889a3 ("esp.c: prevent cmdfifo over= flow in esp_cdb_ready()") subtracted cmdfifo_cdb_offset from fifo8_num_used() to calculate the outstanding cmdfifo length, but this is incorrect because fifo8_num_used() can also include wraparound data. Instead calculate the maximum offset used by scsi_cdb_length() which is just the first byte after cmdfifo_cdb_offset, and then peek the entire content of the cmdfifo. The fifo8_peek_bufptr() result will then return the maximum length of remaining data up to the end of the internal cmdfifo array, which can then be used for the overflow check. Signed-off-by: Mark Cave-Ayland Fixes: 3cc70889a3 ("esp.c: prevent cmdfifo overflow in esp_cdb_ready()") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3082 Reviewed-by: Philippe Mathieu-Daud=C3=A9 Link: https://lore.kernel.org/r/20250925122846.527615-2-mark.cave-ayland@il= ande.co.uk Signed-off-by: Paolo Bonzini (cherry picked from commit 36ec1a829a07cd9a926b2f0ddfa5079c8dc9dae5) Signed-off-by: Michael Tokarev diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c index ac841dc32e..59df9ee683 100644 --- a/hw/scsi/esp.c +++ b/hw/scsi/esp.c @@ -447,7 +447,9 @@ static void write_response(ESPState *s) =20 static bool esp_cdb_ready(ESPState *s) { - int len =3D fifo8_num_used(&s->cmdfifo) - s->cmdfifo_cdb_offset; + /* scsi_cdb_length() only reads the first byte */ + int limit =3D s->cmdfifo_cdb_offset + 1; + int len =3D fifo8_num_used(&s->cmdfifo); const uint8_t *pbuf; uint32_t n; int cdblen; @@ -457,7 +459,7 @@ static bool esp_cdb_ready(ESPState *s) } =20 pbuf =3D fifo8_peek_bufptr(&s->cmdfifo, len, &n); - if (n < len) { + if (n < limit) { /* * In normal use the cmdfifo should never wrap, but include this c= heck * to prevent a malicious guest from reading past the end of the --=20 2.47.3