From 926cde5f3e4d2504ed161ed0cb771ac7cad6fd11 Mon Sep 17 00:00:00 2001
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>

Upstream-Status: Backport
CVE: CVE-2016-6351 patch1
Signed-off-by: Armin Kuster <akuster@mvista.com>

---
 hw/scsi/esp.c         | 6 ++++--
 include/hw/scsi/esp.h | 3 ++-
 2 files changed, 6 insertions(+), 3 deletions(-)

Index: qemu-2.4.0/hw/scsi/esp.c
===================================================================
--- qemu-2.4.0.orig/hw/scsi/esp.c
+++ qemu-2.4.0/hw/scsi/esp.c
@@ -241,6 +241,8 @@ 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);
         s->ti_size = 0;
         s->cmdlen = 0;
@@ -340,7 +342,7 @@ 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
@@ -446,7 +448,7 @@ void esp_reg_write(ESPState *s, uint32_t
         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();
Index: qemu-2.4.0/include/hw/scsi/esp.h
===================================================================
--- qemu-2.4.0.orig/include/hw/scsi/esp.h
+++ qemu-2.4.0/include/hw/scsi/esp.h
@@ -14,6 +14,7 @@ void esp_init(hwaddr espaddr, int it_shi
 
 #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;