Fix CVE-2016-6490: virtio: check vring descriptor buffer length

[pve-qemu-kvm.git] / debian / patches / extra / 0001-scsi-esp-make-cmdbuf-big-enough-for-maximum-CDB-size.patch

From 0988f56451a246d5b72484e0c6dd37fe1bd69d12 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 1/2] 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>

Conflicts:
	hw/scsi/esp.c
commit ff589551c8e8e9e95e211b9d8daafb4ed39f1aec
scsi: esp: check TI buffer index before read/write

added additional control variables to ESPState as ti_size
wasn't enough, we thus ran in a conflict here, use only
ti_size for now as conflict resolution.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
 hw/scsi/esp.c         | 10 ++++++++--
 include/hw/scsi/esp.h |  3 ++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 8961be2..e533522 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -243,6 +243,8 @@ 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;
@@ -342,7 +344,7 @@ 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
@@ -448,7 +450,11 @@ void esp_reg_write(ESPState *s, uint32_t saddr, uint64_t val)
         break;
     case ESP_FIFO:
         if (s->do_cmd) {
-            s->cmdbuf[s->cmdlen++] = val & 0xff;
+            if (s->cmdlen < ESP_CMDBUF_SZ) {
+                s->cmdbuf[s->cmdlen++] = val & 0xff;
+            } else {
+                trace_esp_error_fifo_overrun();
+            }
         } else if (s->ti_size == TI_BUFSZ - 1) {
             trace_esp_error_fifo_overrun();
         } else {
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;
 
-- 
2.1.4