[Qemu-devel] [PATCH v2] hw/sd: fix out-of-bounds check for multi block reads

[Michael Olbrich <m.olbrich@pengutronix.de>]

The current code checks if the next block exceeds the size of the card.
This generates an error while reading the last block of the card.
Do the out-of-bounds check when starting to read a new block to fix this.

This issue became visible with increased error checking in Linux 4.13.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
---

Changes in v2:
 - fixed warning

I'm not quite sure if 0x00 is the correct return value, but it's used
elsewhere in the same function when an error occurs, so it seems
reasonable.

 hw/sd/sd.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/hw/sd/sd.c b/hw/sd/sd.c
index ba47bff4db80..35347a5bbcde 100644
--- a/hw/sd/sd.c
+++ b/hw/sd/sd.c
@@ -1797,8 +1797,13 @@ uint8_t sd_read_data(SDState *sd)
         break;
 
     case 18:	/* CMD18:  READ_MULTIPLE_BLOCK */
-        if (sd->data_offset == 0)
+        if (sd->data_offset == 0) {
+            if (sd->data_start + io_len > sd->size) {
+                sd->card_status |= ADDRESS_ERROR;
+                return 0x00;
+            }
             BLK_READ_BLOCK(sd->data_start, io_len);
+        }
         ret = sd->data[sd->data_offset ++];
 
         if (sd->data_offset >= io_len) {
@@ -1812,11 +1817,6 @@ uint8_t sd_read_data(SDState *sd)
                     break;
                 }
             }
-
-            if (sd->data_start + io_len > sd->size) {
-                sd->card_status |= ADDRESS_ERROR;
-                break;
-            }
         }
         break;
 
-- 
2.14.1