From: Prasad J Pandit <pjp@fedoraproject.org>

Date: Thu, 16 Jun 2016 00:22:35 +0200

Subject: [PATCH] scsi: esp: make cmdbuf big enough for maximum CDB size

While doing DMA read into ESP command buffer 's->cmdbuf', it could

write past the 's->cmdbuf' area, if it was transferring more than 16

bytes.  Increase the command buffer size to 32, which is maximum when

's->do_cmd' is set, and add a check on 'len' to avoid OOB access.

Reported-by: Li Qiang <liqiang6-s@360.cn>

Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

(cherry picked from commit 926cde5f3e4d2504ed161ed0cb771ac7cad6fd11)

---

 hw/scsi/esp.c         | 6 ++++--

 include/hw/scsi/esp.h | 3 ++-

 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c

index 68d3e4d..b4601ad 100644

--- a/hw/scsi/esp.c

+++ b/hw/scsi/esp.c

@@ -248,6 +248,8 @@ static void esp_do_dma(ESPState *s)

     len = s->dma_left;

     if (s->do_cmd) {

         trace_esp_do_dma(s->cmdlen, len);

+        assert (s->cmdlen <= sizeof(s->cmdbuf) &&

+                len <= sizeof(s->cmdbuf) - s->cmdlen);

         s->dma_memory_read(s->dma_opaque, &s->cmdbuf[s->cmdlen], len);

         return;

     }

@@ -345,7 +347,7 @@ static void handle_ti(ESPState *s)

     s->dma_counter = dmalen;

     if (s->do_cmd)

-        minlen = (dmalen < 32) ? dmalen : 32;

+        minlen = (dmalen < ESP_CMDBUF_SZ) ? dmalen : ESP_CMDBUF_SZ;

     else if (s->ti_size < 0)

         minlen = (dmalen < -s->ti_size) ? dmalen : -s->ti_size;

     else

@@ -451,7 +453,7 @@ void esp_reg_write(ESPState *s, uint32_t saddr, uint64_t val)

         break;

     case ESP_FIFO:

         if (s->do_cmd) {

-            if (s->cmdlen < TI_BUFSZ) {

+            if (s->cmdlen < ESP_CMDBUF_SZ) {

                 s->cmdbuf[s->cmdlen++] = val & 0xff;

             } else {

                 trace_esp_error_fifo_overrun();

diff --git a/include/hw/scsi/esp.h b/include/hw/scsi/esp.h

index 6c79527..d2c4886 100644

--- a/include/hw/scsi/esp.h

+++ b/include/hw/scsi/esp.h

@@ -14,6 +14,7 @@ void esp_init(hwaddr espaddr, int it_shift,

 #define ESP_REGS 16

 #define TI_BUFSZ 16

+#define ESP_CMDBUF_SZ 32

 typedef struct ESPState ESPState;

@@ -31,7 +32,7 @@ struct ESPState {

     SCSIBus bus;

     SCSIDevice *current_dev;

     SCSIRequest *current_req;

-    uint8_t cmdbuf[TI_BUFSZ];

+    uint8_t cmdbuf[ESP_CMDBUF_SZ];

     uint32_t cmdlen;

     uint32_t do_cmd;