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[PATCH 1/4] esp: don't underflow cmdfifo if no message out/command data
From: |
Mark Cave-Ayland |
Subject: |
[PATCH 1/4] esp: don't underflow cmdfifo if no message out/command data is present |
Date: |
Tue, 16 Mar 2021 23:30:21 +0000 |
If a guest sends a TI (Transfer Information) command without previously sending
any message out/command phase data then cmdfifo will underflow triggering an
assert reading the IDENTIFY byte.
Buglink: https://bugs.launchpad.net/qemu/+bug/1919035
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
hw/scsi/esp.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 507ab363bc..5d3f1ccbc8 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -318,18 +318,24 @@ static void do_busid_cmd(ESPState *s, uint8_t busid)
static void do_cmd(ESPState *s)
{
- uint8_t busid = fifo8_pop(&s->cmdfifo);
+ uint8_t busid;
uint32_t n;
- s->cmdfifo_cdb_offset--;
+ if (fifo8_num_used(&s->cmdfifo)) {
+ busid = fifo8_pop(&s->cmdfifo);
- /* Ignore extended messages for now */
- if (s->cmdfifo_cdb_offset) {
- fifo8_pop_buf(&s->cmdfifo, s->cmdfifo_cdb_offset, &n);
- s->cmdfifo_cdb_offset = 0;
- }
+ if (s->cmdfifo_cdb_offset) {
+ s->cmdfifo_cdb_offset--;
+
+ /* Ignore extended messages for now */
+ if (s->cmdfifo_cdb_offset) {
+ fifo8_pop_buf(&s->cmdfifo, s->cmdfifo_cdb_offset, &n);
+ s->cmdfifo_cdb_offset = 0;
+ }
+ }
- do_busid_cmd(s, busid);
+ do_busid_cmd(s, busid);
+ }
}
static void satn_pdma_cb(ESPState *s)
--
2.20.1