From patchwork Wed Mar 17 23:02:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Cave-Ayland X-Patchwork-Id: 1455035 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) 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=) 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 ozlabs.org (Postfix) with ESMTPS id 4F15Qw4B6kz9sVm for ; Thu, 18 Mar 2021 10:07:36 +1100 (AEDT) Received: from localhost ([::1]:51476 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lMfGI-0006fr-K1 for incoming@patchwork.ozlabs.org; Wed, 17 Mar 2021 19:07:34 -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 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+incoming=patchwork.ozlabs.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 Tested-by: Alexander Bulekov --- 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));