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[PULL,07/13] esp: ensure cmdfifo is not empty and current_dev is non-NULL

Message ID 20210412222048.22818-8-mark.cave-ayland@ilande.co.uk
State New
Headers show
Series [PULL,01/13] esp: fix setting of ESPState mig_version_id when launching QEMU with -S option | expand

Commit Message

Mark Cave-Ayland April 12, 2021, 10:20 p.m. UTC
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

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>
 hw/scsi/esp.c | 3 +++
 1 file changed, 3 insertions(+)
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diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index bf22785b79..904fa3179c 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -284,6 +284,9 @@  static void do_busid_cmd(ESPState *s, uint8_t busid)
     lun = busid & 7;
     cmdlen = fifo8_num_used(&s->cmdfifo);
+    if (!cmdlen || !s->current_dev) {
+        return;
+    }
     esp_fifo_pop_buf(&s->cmdfifo, buf, cmdlen);
     current_lun = scsi_device_find(&s->bus, 0, s->current_dev->id, lun);