[Qemu-devel] [PATCH] scsi: avoid an off-by-one error in megasas_mmio_write

[P J P <ppandit@redhat.com>]

From: Prasad J Pandit <pjp@fedoraproject.org>

While reading magic sequence(MFI_SEQ) in megasas_mmio_write,
an off-by-one error could occur as 's->adp_reset' index is not
reset after reading the last sequence.

Reported-by: YY Z <bigbird475958471@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/scsi/megasas.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c
index 84b8caf..804122a 100644
--- a/hw/scsi/megasas.c
+++ b/hw/scsi/megasas.c
@@ -2138,15 +2138,15 @@ static void megasas_mmio_write(void *opaque, hwaddr addr,
     case MFI_SEQ:
         trace_megasas_mmio_writel("MFI_SEQ", val);
         /* Magic sequence to start ADP reset */
-        if (adp_reset_seq[s->adp_reset] == val) {
-            s->adp_reset++;
+        if (adp_reset_seq[s->adp_reset++] == val) {
+            if (s->adp_reset == 6) {
+                s->adp_reset = 0;
+                s->diag = MFI_DIAG_WRITE_ENABLE;
+            }
         } else {
             s->adp_reset = 0;
             s->diag = 0;
         }
-        if (s->adp_reset == 6) {
-            s->diag = MFI_DIAG_WRITE_ENABLE;
-        }
         break;
     case MFI_DIAG:
         trace_megasas_mmio_writel("MFI_DIAG", val);
-- 
2.9.3