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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7808CC433DB for ; Wed, 17 Mar 2021 23:08:08 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 24E5464E42 for ; Wed, 17 Mar 2021 23:08:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 24E5464E42 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ilande.co.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:52852 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lMfGp-0007Dk-2G for qemu-devel@archiver.kernel.org; Wed, 17 Mar 2021 19:08:07 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43540) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMfBq-0002iT-U6 for qemu-devel@nongnu.org; Wed, 17 Mar 2021 19:02:58 -0400 Received: from mail.ilande.co.uk ([2001:41c9:1:41f::167]:35398 helo=mail.default.ilande.uk0.bigv.io) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMfBn-0005RQ-UC for qemu-devel@nongnu.org; Wed, 17 Mar 2021 19:02:58 -0400 Received: from host86-148-103-84.range86-148.btcentralplus.com ([86.148.103.84] helo=kentang.home) by mail.default.ilande.uk0.bigv.io with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lMfBm-0006Bn-0a; Wed, 17 Mar 2021 23:03:00 +0000 From: Mark Cave-Ayland To: qemu-devel@nongnu.org, alxndr@bu.edu, laurent@vivier.eu, pbonzini@redhat.com Date: Wed, 17 Mar 2021 23:02:21 +0000 Message-Id: <20210317230223.24854-5-mark.cave-ayland@ilande.co.uk> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210317230223.24854-1-mark.cave-ayland@ilande.co.uk> References: <20210317230223.24854-1-mark.cave-ayland@ilande.co.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 86.148.103.84 X-SA-Exim-Mail-From: mark.cave-ayland@ilande.co.uk Subject: [PATCH v2 4/6] esp: don't underflow fifo when writing to the device X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on mail.default.ilande.uk0.bigv.io) Received-SPF: pass client-ip=2001:41c9:1:41f::167; envelope-from=mark.cave-ayland@ilande.co.uk; helo=mail.default.ilande.uk0.bigv.io X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" When writing to the device make sure that the fifo is not empty, otherwise the fifo will underflow triggering an assert. Buglink: https://bugs.launchpad.net/qemu/+bug/1909247 Signed-off-by: Mark Cave-Ayland --- hw/scsi/esp.c | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-) diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c index ae362c9dfb..bb57125035 100644 --- a/hw/scsi/esp.c +++ b/hw/scsi/esp.c @@ -509,18 +509,20 @@ static void do_dma_pdma_cb(ESPState *s) /* Copy FIFO data to device */ len = MIN(s->async_len, ESP_FIFO_SZ); len = MIN(len, fifo8_num_used(&s->fifo)); - memcpy(s->async_buf, fifo8_pop_buf(&s->fifo, len, &n), len); - s->async_buf += n; - s->async_len -= n; - s->ti_size += n; - - if (n < len) { - /* Unaligned accesses can cause FIFO wraparound */ - len = len - n; + if (len) { memcpy(s->async_buf, fifo8_pop_buf(&s->fifo, len, &n), len); s->async_buf += n; s->async_len -= n; s->ti_size += n; + + if (n < len) { + /* Unaligned accesses can cause FIFO wraparound */ + len = len - n; + memcpy(s->async_buf, fifo8_pop_buf(&s->fifo, len, &n), len); + s->async_buf += n; + s->async_len -= n; + s->ti_size += n; + } } if (s->async_len == 0) { @@ -730,10 +732,12 @@ static void esp_do_nodma(ESPState *s) if (to_device) { len = MIN(fifo8_num_used(&s->fifo), ESP_FIFO_SZ); - memcpy(s->async_buf, fifo8_pop_buf(&s->fifo, len, &n), len); - s->async_buf += len; - s->async_len -= len; - s->ti_size += len; + if (len) { + memcpy(s->async_buf, fifo8_pop_buf(&s->fifo, len, &n), len); + s->async_buf += len; + s->async_len -= len; + s->ti_size += len; + } } else { len = MIN(s->ti_size, s->async_len); len = MIN(len, fifo8_num_free(&s->fifo)); -- 2.20.1