libahci: Fix bug in storing EM messages

In function ahci_store_em_buffer(), if the input (signed char*) buffer
contains negative data, the constructed 32-bit long message data may
be wrong.

Signed-off-by: Harry Zhang <harry.zhang@amd.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 261f86d102e8..81e772a94d59 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -324,6 +324,7 @@ static ssize_t ahci_store_em_buffer(struct device *dev,
         struct ahci_host_priv *hpriv = ap->host->private_data;
         void __iomem *mmio = hpriv->mmio;
         void __iomem *em_mmio = mmio + hpriv->em_loc;
+        const unsigned char *msg_buf = buf;
         u32 em_ctl, msg;
         unsigned long flags;
         int i;
@@ -343,8 +344,8 @@ static ssize_t ahci_store_em_buffer(struct device *dev,
         }
 
         for (i = 0; i < size; i += 4) {
-                msg = buf[i] | buf[i + 1] << 8 |
-                      buf[i + 2] << 16 | buf[i + 3] << 24;
+                msg = msg_buf[i] | msg_buf[i + 1] << 8 |
+                      msg_buf[i + 2] << 16 | msg_buf[i + 3] << 24;
                 writel(msg, em_mmio + i);
         }