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scsi: Allocate SCSITargetReq r->buf dynamically [CVE-2013-4344]

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r->buf is hardcoded to 2056 which is (256 + 1) * 8, allowing 256 luns at
most. If more than 256 luns are specified by user, we have buffer
overflow in scsi_target_emulate_report_luns.

To fix, we allocate the buffer dynamically.

Signed-off-by: Asias He <asias@redhat.com>
Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Asias He 2013-10-09 15:41:03 +08:00 committed by Paolo Bonzini
parent 24c7608a5d
commit 846424350b
2 changed files with 36 additions and 11 deletions
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45
hw/scsi/scsi-bus.c
View File

@ -11,6 +11,8 @@ static char *scsibus_get_dev_path(DeviceState *dev);
static char *scsibus_get_fw_dev_path(DeviceState *dev);
static int scsi_req_parse(SCSICommand *cmd, SCSIDevice *dev, uint8_t *buf);
static void scsi_req_dequeue(SCSIRequest *req);
static uint8_t *scsi_target_alloc_buf(SCSIRequest *req, size_t len);
static void scsi_target_free_buf(SCSIRequest *req);
static Property scsi_props[] = {
DEFINE_PROP_UINT32("channel", SCSIDevice, channel, 0),
@ -317,7 +319,8 @@ typedef struct SCSITargetReq SCSITargetReq;
struct SCSITargetReq {
SCSIRequest req;
int len;
uint8_t buf[2056];
uint8_t *buf;
int buf_len;
};
static void store_lun(uint8_t *outbuf, int lun)
@ -361,14 +364,12 @@ static bool scsi_target_emulate_report_luns(SCSITargetReq *r)
if (!found_lun0) {
n += 8;
}
len = MIN(n + 8, r->req.cmd.xfer & ~7);
if (len > sizeof(r->buf)) {
/* TODO: > 256 LUNs? */
return false;
}
scsi_target_alloc_buf(&r->req, n + 8);
len = MIN(n + 8, r->req.cmd.xfer & ~7);
memset(r->buf, 0, len);
stl_be_p(&r->buf, n);
stl_be_p(&r->buf[0], n);
i = found_lun0 ? 8 : 16;
QTAILQ_FOREACH(kid, &r->req.bus->qbus.children, sibling) {
DeviceState *qdev = kid->child;
@ -387,6 +388,9 @@ static bool scsi_target_emulate_report_luns(SCSITargetReq *r)
static bool scsi_target_emulate_inquiry(SCSITargetReq *r)
{
assert(r->req.dev->lun != r->req.lun);
scsi_target_alloc_buf(&r->req, SCSI_INQUIRY_LEN);
if (r->req.cmd.buf[1] & 0x2) {
/* Command support data - optional, not implemented */
return false;
@ -411,7 +415,7 @@ static bool scsi_target_emulate_inquiry(SCSITargetReq *r)
return false;
}
/* done with EVPD */
assert(r->len < sizeof(r->buf));
assert(r->len < r->buf_len);
r->len = MIN(r->req.cmd.xfer, r->len);
return true;
}
@ -422,7 +426,7 @@ static bool scsi_target_emulate_inquiry(SCSITargetReq *r)
}
/* PAGE CODE == 0 */
r->len = MIN(r->req.cmd.xfer, 36);
r->len = MIN(r->req.cmd.xfer, SCSI_INQUIRY_LEN);
memset(r->buf, 0, r->len);
if (r->req.lun != 0) {
r->buf[0] = TYPE_NO_LUN;
@ -455,8 +459,9 @@ static int32_t scsi_target_send_command(SCSIRequest *req, uint8_t *buf)
}
break;
case REQUEST_SENSE:
scsi_target_alloc_buf(&r->req, SCSI_SENSE_LEN);
r->len = scsi_device_get_sense(r->req.dev, r->buf,
MIN(req->cmd.xfer, sizeof r->buf),
MIN(req->cmd.xfer, r->buf_len),
(req->cmd.buf[1] & 1) == 0);
if (r->req.dev->sense_is_ua) {
scsi_device_unit_attention_reported(req->dev);
@ -501,11 +506,29 @@ static uint8_t *scsi_target_get_buf(SCSIRequest *req)
return r->buf;
}
static uint8_t *scsi_target_alloc_buf(SCSIRequest *req, size_t len)
{
SCSITargetReq *r = DO_UPCAST(SCSITargetReq, req, req);
r->buf = g_malloc(len);
r->buf_len = len;
return r->buf;
}
static void scsi_target_free_buf(SCSIRequest *req)
{
SCSITargetReq *r = DO_UPCAST(SCSITargetReq, req, req);
g_free(r->buf);
}
static const struct SCSIReqOps reqops_target_command = {
.size = sizeof(SCSITargetReq),
.send_command = scsi_target_send_command,
.read_data = scsi_target_read_data,
.get_buf = scsi_target_get_buf,
.free_req = scsi_target_free_buf,
};
@ -1365,7 +1388,7 @@ int scsi_build_sense(uint8_t *in_buf, int in_len,
buf[7] = 10;
buf[12] = sense.asc;
buf[13] = sense.ascq;
return MIN(len, 18);
return MIN(len, SCSI_SENSE_LEN);
} else {
/* Return descriptor format sense buffer */
buf[0] = 0x72;

2
include/hw/scsi/scsi.h
View File

@ -9,6 +9,8 @@
#define MAX_SCSI_DEVS 255
#define SCSI_CMD_BUF_SIZE 16
#define SCSI_SENSE_LEN 18
#define SCSI_INQUIRY_LEN 36
typedef struct SCSIBus SCSIBus;
typedef struct SCSIBusInfo SCSIBusInfo;