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Backport of:
From 99545751734035b76bd372c4e7215bb337428d89 Mon Sep 17 00:00:00 2001
From: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Date: Wed, 7 Apr 2021 20:57:55 +0100
Subject: [PATCH] esp: ensure cmdfifo is not empty and current_dev is non-NULL
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit
When about to execute a SCSI command, ensure that cmdfifo is not empty and
current_dev is non-NULL. This can happen if the guest tries to execute a TI
(Transfer Information) command without issuing one of the select commands
first.
Buglink: https://bugs.launchpad.net/qemu/+bug/1910723
Buglink: https://bugs.launchpad.net/qemu/+bug/1909247
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20210407195801.685-7-mark.cave-ayland@ilande.co.uk>
CVE: CVE-2020-35505
Upstream-Status: Backport [import from ubuntu https://git.launchpad.net/ubuntu/+source/qemu/tree/debian/patches/CVE-2020-35505.patch?h=ubuntu/focal-security Upstream commit https://github.com/qemu/qemu/commit/99545751734035b76bd372c4e7215bb337428d89 ]
Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com>
Signed-off-by: Emily Vekariya <emily.vekariya@einfochips.com>
---
hw/scsi/esp.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index c7d701bf..c2a67bc8 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -193,6 +193,10 @@ static void do_busid_cmd(ESPState *s, uint8_t *buf, uint8_t busid)
trace_esp_do_busid_cmd(busid);
lun = busid & 7;
+
+ if (!s->current_dev) {
+ return;
+ }
current_lun = scsi_device_find(&s->bus, 0, s->current_dev->id, lun);
s->current_req = scsi_req_new(current_lun, 0, lun, buf, s);
datalen = scsi_req_enqueue(s->current_req);
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