Commit 84642435 authored by Asias He's avatar Asias He Committed by Paolo Bonzini
Browse files

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



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: default avatarAsias He <asias@redhat.com>
Tested-by: default avatarMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 24c7608a

hw/scsi/scsi-bus.c

+34 −11
Original line number Diff line number Diff line
@@ -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;

include/hw/scsi/scsi.h

+2 −0
Original line number Diff line number Diff line
@@ -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;