Index: firmware/target/arm/as3525/sd-as3525v2.c
===================================================================
--- firmware/target/arm/as3525/sd-as3525v2.c    (revision 29635)
+++ firmware/target/arm/as3525/sd-as3525v2.c    (working copy)
@@ -844,11 +844,6 @@
         goto sd_transfer_error_no_dma;
     }
 
-    if((start+count) > card_info[drive].numblocks)
-    {
-        ret = -19;
-        goto sd_transfer_error_no_dma;
-    }
 
     /* skip SanDisk OF */
     if (drive == INTERNAL_AS3525)
@@ -866,6 +861,12 @@
             goto sd_transfer_error_no_dma;
     }
 
+    if((drive == INTERNAL_AS3525 && (start+count-AMS_OF_SIZE) > card_info[drive].numblocks) || (drive != INTERNAL_AS3525 && (start+count) > card_info[drive].numblocks))
+    {
+        ret = -19;
+        goto sd_transfer_error_no_dma;
+    }
+
     /*  CMD7 w/rca: Select card to put it in TRAN state */
     if(!send_cmd(drive, SD_SELECT_CARD, card_info[drive].rca, MCI_NO_RESP, NULL))
     {