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[PATCH v4 for-6.0 07/12] esp: don't underflow cmdfifo in do_cmd()
From: |
Mark Cave-Ayland |
Subject: |
[PATCH v4 for-6.0 07/12] esp: don't underflow cmdfifo in do_cmd() |
Date: |
Wed, 7 Apr 2021 20:57:56 +0100 |
If the guest tries to execute a CDB when cmdfifo is not empty before the start
of the message out phase then clearing the message out phase data will cause
cmdfifo to underflow due to cmdfifo_cdb_offset being larger than the amount of
data within.
Since this can only occur by issuing deliberately incorrect instruction
sequences, ensure that the maximum length of esp_fifo_pop_buf() is limited to
the size of the data within cmdfifo.
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>
---
hw/scsi/esp.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 4decbbfc29..7f49522e1d 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -319,13 +319,15 @@ 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 = esp_fifo_pop(&s->cmdfifo);
+ int len;
s->cmdfifo_cdb_offset--;
/* Ignore extended messages for now */
if (s->cmdfifo_cdb_offset) {
- esp_fifo_pop_buf(&s->cmdfifo, NULL, s->cmdfifo_cdb_offset);
+ len = MIN(s->cmdfifo_cdb_offset, fifo8_num_used(&s->cmdfifo));
+ esp_fifo_pop_buf(&s->cmdfifo, NULL, len);
s->cmdfifo_cdb_offset = 0;
}
--
2.20.1
- [PATCH v4 for-6.0 00/12] esp: fix asserts/segfaults discovered by fuzzer, Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 01/12] esp: always check current_req is not NULL before use in DMA callbacks, Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 02/12] esp: rework write_response() to avoid using the FIFO for DMA transactions, Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 03/12] esp: consolidate esp_cmdfifo_push() into esp_fifo_push(), Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 04/12] esp: consolidate esp_cmdfifo_pop() into esp_fifo_pop(), Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 05/12] esp: introduce esp_fifo_pop_buf() and use it instead of fifo8_pop_buf(), Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 06/12] esp: ensure cmdfifo is not empty and current_dev is non-NULL, Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 07/12] esp: don't underflow cmdfifo in do_cmd(),
Mark Cave-Ayland <=
- [PATCH v4 for-6.0 08/12] esp: don't overflow cmdfifo in get_cmd(), Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 09/12] esp: don't overflow cmdfifo if TC is larger than the cmdfifo size, Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 10/12] esp: don't reset async_len directly in esp_select() if cancelling request, Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 11/12] esp: ensure that do_cmd is set to zero before submitting an ESP select command, Mark Cave-Ayland, 2021/04/07
- [PATCH v4 for-6.0 12/12] tests/qtest: add tests for am53c974 device, Mark Cave-Ayland, 2021/04/07
- Re: [PATCH v4 for-6.0 00/12] esp: fix asserts/segfaults discovered by fuzzer, Mark Cave-Ayland, 2021/04/09