Re: [PATCH] tests/qtest: add one more test for the am53c974

[Mark Cave-Ayland]

On 02/04/2021 17:20, Alexander Bulekov wrote:

> Original crash:
> qemu-fuzz-i386: ../hw/scsi/esp.c:791: void esp_transfer_data(SCSIRequest *, 
> uint32_t): Assertion `!s->do_cmd' failed.
> ==257532== ERROR: libFuzzer: deadly signal
> __assert_fail assert/assert.c:101:3
> esp_transfer_data hw/scsi/esp.c:791:5
> scsi_req_data hw/scsi/scsi-bus.c:1412:9
> scsi_disk_emulate_read_data hw/scsi/scsi-disk.c:1407:9
> scsi_req_continue hw/scsi/scsi-bus.c:1394:9
> do_busid_cmd hw/scsi/esp.c:317:9
> handle_s_without_atn hw/scsi/esp.c:393:9
> esp_reg_write hw/scsi/esp.c:1029:13
> esp_pci_io_write hw/scsi/esp-pci.c:215:9
> memory_region_write_accessor softmmu/memory.c:491:5
> access_with_adjusted_size softmmu/memory.c:552:18
> memory_region_dispatch_write softmmu/memory.c:1502:16
> flatview_write_continue softmmu/physmem.c:2746:23
> flatview_write softmmu/physmem.c:2786:14
> address_space_write softmmu/physmem.c:2878:18
> cpu_outl softmmu/ioport.c:80:5
>
> Based-on: <20210401074933.9923-1-mark.cave-ayland@ilande.co.uk>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> ---
>   tests/qtest/am53c974-test.c | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
>
> The patch took care of the handle_satn_stop assert. Here's a test case
> for the other assert.

Even though I can't reproduce the assert() here, looking at the code I think I can 
see how do_cmd is not being reset when a DMA command is issued. Does the following 
solve the outstanding fuzzer asserts?

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 0037197bdb..b668acef82 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -357,6 +357,7 @@ static void handle_satn(ESPState *s)
     cmdlen = get_cmd(s, ESP_CMDFIFO_SZ);
     if (cmdlen > 0) {
         s->cmdfifo_cdb_offset = 1;
+        s->do_cmd = 0;
         do_cmd(s);
     } else if (cmdlen == 0) {
         s->do_cmd = 1;
@@ -390,6 +391,7 @@ static void handle_s_without_atn(ESPState *s)
     cmdlen = get_cmd(s, ESP_CMDFIFO_SZ);
     if (cmdlen > 0) {
         s->cmdfifo_cdb_offset = 0;
+        s->do_cmd = 0;
         do_busid_cmd(s, 0);
     } else if (cmdlen == 0) {
         s->do_cmd = 1;


ATB,

Mark.