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[1/2] scsi: check command buffer length before write(CVE-2016-4439)

Message ID 1463654371-11169-2-git-send-email-ppandit@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Prasad Pandit May 19, 2016, 10:39 a.m. UTC 
From: Prasad J Pandit <pjp@fedoraproject.org>

The 53C9X Fast SCSI Controller(FSC) comes with an internal 16-byte
FIFO buffer. It is used to handle command and data transfer. While
writing to this command buffer 's->cmdbuf[TI_BUFSZ=16]', a check
was missing to validate input length. Add check to avoid OOB write
access.

Fixes CVE-2016-4439
Reported-by: Li Qiang <liqiang6-s@360.cn>

Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/scsi/esp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
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Patch

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 8961be2..01497e6 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -448,7 +448,11 @@  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 < TI_BUFSZ) {
+                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 {