From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 21 Jul 2015 06:59:39 +0000 (+0200)
Subject: scsi: fix buffer overflow in scsi_req_parse_cdb (CVE-2015-5158)
X-Git-Tag: qemu-xen-4.6.0-rc1~11
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=e40ae8730e83e25f160c7576dd32d882bf2a3846;p=qemu-upstream-4.6-testing.git

scsi: fix buffer overflow in scsi_req_parse_cdb (CVE-2015-5158)

This is a guest-triggerable buffer overflow present in QEMU 2.2.0
and newer.  scsi_cdb_length returns -1 as an error value, but the
caller does not check it.

Luckily, the massive overflow means that QEMU will just SIGSEGV,
making the impact much smaller.

upstream-commit-id: c170aad8b057223b1139d72e5ce7acceafab4fa9

Reported-by: Zhu Donghai (朱东海) <donghai.zdh@alibaba-inc.com>
Fixes: 1894df02811f6b79ea3ffbf1084599d96f316173
Reviewed-by: Fam Zheng <famz@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---

diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index 9b740a3cf..8e4a986cb 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -1234,10 +1234,15 @@ int scsi_cdb_length(uint8_t *buf) {
 int scsi_req_parse_cdb(SCSIDevice *dev, SCSICommand *cmd, uint8_t *buf)
 {
     int rc;
+    int len;
 
     cmd->lba = -1;
-    cmd->len = scsi_cdb_length(buf);
+    len = scsi_cdb_length(buf);
+    if (len < 0) {
+        return -1;
+    }
 
+    cmd->len = len;
     switch (dev->type) {
     case TYPE_TAPE:
         rc = scsi_req_stream_xfer(cmd, dev, buf);