[PATCH] ipmi:smbus: Add a check around a memcpy

[minyard]

From: Corey Minyard <cminyard@mvista.com>

In one case:

  memcpy(sid->inmsg + sid->inlen, buf, len);

if len == 0 then sid->inmsg + sig->inlen can point to one past the inmsg
array if the array is full.  We have to allow len == 0 due to some
vagueness in the spec, but we don't have to call memcpy.

Found by Coverity.  This is not a problem in practice, but the results
are technically (maybe) undefined.  So make Coverity happy.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
---
 hw/ipmi/smbus_ipmi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

I think this should do it.

diff --git a/hw/ipmi/smbus_ipmi.c b/hw/ipmi/smbus_ipmi.c
index 9ef9112dd5..d0991ab7f9 100644
--- a/hw/ipmi/smbus_ipmi.c
+++ b/hw/ipmi/smbus_ipmi.c
@@ -281,7 +281,9 @@ static int ipmi_write_data(SMBusDevice *dev, uint8_t *buf, 
uint8_t len)
              */
             send = true;
         }
-        memcpy(sid->inmsg + sid->inlen, buf, len);
+        if (len > 0) {
+            memcpy(sid->inmsg + sid->inlen, buf, len);
+        }
         sid->inlen += len;
         break;
     }
-- 
2.25.1