Staging: hv: storvsc: Fix a bug in copy_from_bounce_buffer()

Fix a bug in copy_from_bounce_buffer().

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/hv/storvsc_drv.c b/drivers/staging/hv/storvsc_drv.c
index 8dafe52e9a69d29eb0e3a913885f3165a9ffc459..c22de062dc49184b65bc9e884b7981ce17524025 100644 (file)
--- a/drivers/staging/hv/storvsc_drv.c
+++ b/drivers/staging/hv/storvsc_drv.c
@@ -880,7 +880,8 @@ cleanup:
 /* Assume the original sgl has enough room */
 static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
                                            struct scatterlist *bounce_sgl,
-                                           unsigned int orig_sgl_count)
+                                           unsigned int orig_sgl_count,
+                                           unsigned int bounce_sgl_count)
 {
        int i;
        int j = 0;
@@ -921,6 +922,24 @@ static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
                                kunmap_atomic((void *)bounce_addr, KM_IRQ0);
                                j++;
 
+                               /*
+                                * It is possible that the number of elements
+                                * in the bounce buffer may not be equal to
+                                * the number of elements in the original
+                                * scatter list. Handle this correctly.
+                                */
+
+                               if (j == bounce_sgl_count) {
+                                       /*
+                                        * We are done; cleanup and return.
+                                        */
+                                       kunmap_atomic((void *)(dest_addr -
+                                                       orig_sgl[i].offset),
+                                                       KM_IRQ0);
+                                       local_irq_restore(flags);
+                                       return total_copied;
+                               }
+
                                /* if we need to use another bounce buffer */
                                if (destlen || i != orig_sgl_count - 1)
                                        bounce_addr =
@@ -1126,7 +1145,8 @@ static void storvsc_command_completion(struct hv_storvsc_request *request)
                if (vm_srb->data_in == READ_TYPE)
                        copy_from_bounce_buffer(scsi_sglist(scmnd),
                                        cmd_request->bounce_sgl,
-                                       scsi_sg_count(scmnd));
+                                       scsi_sg_count(scmnd),
+                                       cmd_request->bounce_sgl_count);
                destroy_bounce_buffer(cmd_request->bounce_sgl,
                                        cmd_request->bounce_sgl_count);
        }