From: Paolo Bonzini <pbonzini@redhat.com>

Date: Thu, 1 Jun 2017 17:23:13 +0200

Subject: [PATCH] megasas: do not read command more than once from frame

Avoid TOC-TOU bugs by passing the frame_cmd down, and checking

cmd->dcmd_opcode instead of cmd->frame->header.frame_cmd.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

(cherry picked from commit 36c327a69d723571f02a7691631667cdb1865ee1)

---

 hw/scsi/megasas.c | 60 +++++++++++++++++++++++--------------------------------

 1 file changed, 25 insertions(+), 35 deletions(-)

diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c

index a3f75c1650..38e0a2f5ef 100644

--- a/hw/scsi/megasas.c

+++ b/hw/scsi/megasas.c

@@ -1591,12 +1591,13 @@ static int megasas_handle_dcmd(MegasasState *s, MegasasCmd *cmd)

 }

 static int megasas_finish_internal_dcmd(MegasasCmd *cmd,

-                                        SCSIRequest *req)

+                                        SCSIRequest *req, size_t resid)

 {

     int retval = MFI_STAT_OK;

     int lun = req->lun;

     trace_megasas_dcmd_internal_finish(cmd->index, cmd->dcmd_opcode, lun);

+    cmd->iov_size -= resid;

     switch (cmd->dcmd_opcode) {

     case MFI_DCMD_PD_GET_INFO:

         retval = megasas_pd_get_info_submit(req->dev, lun, cmd);

@@ -1649,11 +1650,12 @@ static int megasas_enqueue_req(MegasasCmd *cmd, bool is_write)

 }

 static int megasas_handle_scsi(MegasasState *s, MegasasCmd *cmd,

-                               bool is_logical)

+                               int frame_cmd)

 {

     uint8_t *cdb;

     bool is_write;

     struct SCSIDevice *sdev = NULL;

+    bool is_logical = (frame_cmd == MFI_CMD_LD_SCSI_IO);

     cdb = cmd->frame->pass.cdb;

@@ -1661,7 +1663,7 @@ static int megasas_handle_scsi(MegasasState *s, MegasasCmd *cmd,

         if (cmd->frame->header.target_id >= MFI_MAX_LD ||

             cmd->frame->header.lun_id != 0) {

             trace_megasas_scsi_target_not_present(

-                mfi_frame_desc[cmd->frame->header.frame_cmd], is_logical,

+                mfi_frame_desc[frame_cmd], is_logical,

                 cmd->frame->header.target_id, cmd->frame->header.lun_id);

             return MFI_STAT_DEVICE_NOT_FOUND;

         }

@@ -1671,19 +1673,20 @@ static int megasas_handle_scsi(MegasasState *s, MegasasCmd *cmd,

     cmd->iov_size = le32_to_cpu(cmd->frame->header.data_len);

     trace_megasas_handle_scsi(mfi_frame_desc[cmd->frame->header.frame_cmd],

-                              is_logical, cmd->frame->header.target_id,

+    trace_megasas_handle_scsi(mfi_frame_desc[frame_cmd], is_logical,

+                              cmd->frame->header.target_id,

                               cmd->frame->header.lun_id, sdev, cmd->iov_size);

     if (!sdev || (megasas_is_jbod(s) && is_logical)) {

         trace_megasas_scsi_target_not_present(

-            mfi_frame_desc[cmd->frame->header.frame_cmd], is_logical,

+            mfi_frame_desc[frame_cmd], is_logical,

             cmd->frame->header.target_id, cmd->frame->header.lun_id);

         return MFI_STAT_DEVICE_NOT_FOUND;

     }

     if (cmd->frame->header.cdb_len > 16) {

         trace_megasas_scsi_invalid_cdb_len(

-                mfi_frame_desc[cmd->frame->header.frame_cmd], is_logical,

+                mfi_frame_desc[frame_cmd], is_logical,

                 cmd->frame->header.target_id, cmd->frame->header.lun_id,

                 cmd->frame->header.cdb_len);

         megasas_write_sense(cmd, SENSE_CODE(INVALID_OPCODE));

@@ -1703,7 +1706,7 @@ static int megasas_handle_scsi(MegasasState *s, MegasasCmd *cmd,

                             cmd->frame->header.lun_id, cdb, cmd);

     if (!cmd->req) {

         trace_megasas_scsi_req_alloc_failed(

-                mfi_frame_desc[cmd->frame->header.frame_cmd],

+                mfi_frame_desc[frame_cmd],

                 cmd->frame->header.target_id, cmd->frame->header.lun_id);

         megasas_write_sense(cmd, SENSE_CODE(NO_SENSE));

         cmd->frame->header.scsi_status = BUSY;

@@ -1725,11 +1728,11 @@ static int megasas_handle_scsi(MegasasState *s, MegasasCmd *cmd,

     return MFI_STAT_INVALID_STATUS;

 }

-static int megasas_handle_io(MegasasState *s, MegasasCmd *cmd)

+static int megasas_handle_io(MegasasState *s, MegasasCmd *cmd, int frame_cmd)

 {

     uint32_t lba_count, lba_start_hi, lba_start_lo;

     uint64_t lba_start;

-    bool is_write = (cmd->frame->header.frame_cmd == MFI_CMD_LD_WRITE);

+    bool is_write = (frame_cmd == MFI_CMD_LD_WRITE);

     uint8_t cdb[16];

     int len;

     struct SCSIDevice *sdev = NULL;

@@ -1746,20 +1749,20 @@ static int megasas_handle_io(MegasasState *s, MegasasCmd *cmd)

     }

     trace_megasas_handle_io(cmd->index,

-                            mfi_frame_desc[cmd->frame->header.frame_cmd],

+                            mfi_frame_desc[frame_cmd],

                             cmd->frame->header.target_id,

                             cmd->frame->header.lun_id,

                             (unsigned long)lba_start, (unsigned long)lba_count);

     if (!sdev) {

         trace_megasas_io_target_not_present(cmd->index,

-            mfi_frame_desc[cmd->frame->header.frame_cmd],

+            mfi_frame_desc[frame_cmd],

             cmd->frame->header.target_id, cmd->frame->header.lun_id);

         return MFI_STAT_DEVICE_NOT_FOUND;

     }

     if (cmd->frame->header.cdb_len > 16) {

         trace_megasas_scsi_invalid_cdb_len(

-            mfi_frame_desc[cmd->frame->header.frame_cmd], 1,

+            mfi_frame_desc[frame_cmd], 1,

             cmd->frame->header.target_id, cmd->frame->header.lun_id,

             cmd->frame->header.cdb_len);

         megasas_write_sense(cmd, SENSE_CODE(INVALID_OPCODE));

@@ -1781,7 +1784,7 @@ static int megasas_handle_io(MegasasState *s, MegasasCmd *cmd)

                             cmd->frame->header.lun_id, cdb, cmd);

     if (!cmd->req) {

         trace_megasas_scsi_req_alloc_failed(

-            mfi_frame_desc[cmd->frame->header.frame_cmd],

+            mfi_frame_desc[frame_cmd],

             cmd->frame->header.target_id, cmd->frame->header.lun_id);

         megasas_write_sense(cmd, SENSE_CODE(NO_SENSE));

         cmd->frame->header.scsi_status = BUSY;

@@ -1799,23 +1802,11 @@ static int megasas_handle_io(MegasasState *s, MegasasCmd *cmd)

     return MFI_STAT_INVALID_STATUS;

 }

-static int megasas_finish_internal_command(MegasasCmd *cmd,

-                                           SCSIRequest *req, size_t resid)

-{

-    int retval = MFI_STAT_INVALID_CMD;

-

-    if (cmd->frame->header.frame_cmd == MFI_CMD_DCMD) {

-        cmd->iov_size -= resid;

-        retval = megasas_finish_internal_dcmd(cmd, req);

-    }

-    return retval;

-}

-

 static QEMUSGList *megasas_get_sg_list(SCSIRequest *req)

 {

     MegasasCmd *cmd = req->hba_private;

-    if (cmd->frame->header.frame_cmd == MFI_CMD_DCMD) {

+    if (cmd->dcmd_opcode != -1) {

         return NULL;

     } else {

         return &cmd->qsg;

@@ -1829,7 +1820,7 @@ static void megasas_xfer_complete(SCSIRequest *req, uint32_t len)

     trace_megasas_io_complete(cmd->index, len);

-    if (cmd->frame->header.frame_cmd != MFI_CMD_DCMD) {

+    if (cmd->dcmd_opcode != -1) {

         scsi_req_continue(req);

         return;

     }

@@ -1872,7 +1863,7 @@ static void megasas_command_complete(SCSIRequest *req, uint32_t status,

         /*

          * Internal command complete

          */

-        cmd_status = megasas_finish_internal_command(cmd, req, resid);

+        cmd_status = megasas_finish_internal_dcmd(cmd, req, resid);

         if (cmd_status == MFI_STAT_INVALID_STATUS) {

             return;

         }

@@ -1943,6 +1934,7 @@ static void megasas_handle_frame(MegasasState *s, uint64_t frame_addr,

 {

     uint8_t frame_status = MFI_STAT_INVALID_CMD;

     uint64_t frame_context;

+    int frame_cmd;

     MegasasCmd *cmd;

     /*

@@ -1961,7 +1953,8 @@ static void megasas_handle_frame(MegasasState *s, uint64_t frame_addr,

         s->event_count++;

         return;

     }

-    switch (cmd->frame->header.frame_cmd) {

+    frame_cmd = cmd->frame->header.frame_cmd;

+    switch (frame_cmd) {

     case MFI_CMD_INIT:

         frame_status = megasas_init_firmware(s, cmd);

         break;

@@ -1972,18 +1965,15 @@ static void megasas_handle_frame(MegasasState *s, uint64_t frame_addr,

         frame_status = megasas_handle_abort(s, cmd);

         break;

     case MFI_CMD_PD_SCSI_IO:

-        frame_status = megasas_handle_scsi(s, cmd, 0);

-        break;

     case MFI_CMD_LD_SCSI_IO:

-        frame_status = megasas_handle_scsi(s, cmd, 1);

+        frame_status = megasas_handle_scsi(s, cmd, frame_cmd);

         break;

     case MFI_CMD_LD_READ:

     case MFI_CMD_LD_WRITE:

-        frame_status = megasas_handle_io(s, cmd);

+        frame_status = megasas_handle_io(s, cmd, frame_cmd);

         break;

     default:

-        trace_megasas_unhandled_frame_cmd(cmd->index,

-                                          cmd->frame->header.frame_cmd);

+        trace_megasas_unhandled_frame_cmd(cmd->index, frame_cmd);

         s->event_count++;

         break;

     }