scsi: esp: check buffer length before reading scsi command

The 53C9X Fast SCSI Controller(FSC) comes with an internal 16-byte
FIFO buffer. It is used to handle command and data transfer.
Routine get_cmd() in non-DMA mode, uses 'ti_size' to read scsi
command into a buffer. Add check to validate command length against
buffer size to avoid any overrun.

Reported-by: Li Qiang <liqiang6-s@360.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-Id: <1464717207-7549-1-git-send-email-ppandit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit d3cdc49138c30be1d3c2f83d18f85d9fdee95f1a)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 591c8172d50ccc10e00c3fbaffbbbfd7baa08ec8..c2f6f8ff85e6ce1a16bedd4eafc8c82e52125824 100644 (file)
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -98,6 +98,9 @@ static uint32_t get_cmd(ESPState *s, uint8_t *buf, uint8_t buflen)
         s->dma_memory_read(s->dma_opaque, buf, dmalen);
     } else {
         dmalen = s->ti_size;
+        if (dmalen > TI_BUFSZ) {
+            return 0;
+        }
         memcpy(buf, s->ti_buf, dmalen);
         buf[0] = buf[2] >> 5;
     }