[Qemu-devel] [PATCH] pci: fix pci_default_read_config().

[Isaku Yamahata]

address and config_size are both unsigned.
So check which is bigger before minus operation.
Otherwise the result of minus can be unexpected
big value.

Signed-off-by: Isaku Yamahata <address@hidden>
---
 hw/pci.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/hw/pci.c b/hw/pci.c
index 3362842..39a6206 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -988,9 +988,14 @@ uint32_t pci_default_read_config(PCIDevice *d,
                                  uint32_t address, int len)
 {
     uint32_t val = 0;
+    uint32_t config_size = pci_config_size(d);
     assert(len == 1 || len == 2 || len == 4);
-    len = MIN(len, pci_config_size(d) - address);
-    memcpy(&val, d->config + address, len);
+    if (address < config_size) {
+        len = MIN(len, config_size - address);
+        memcpy(&val, d->config + address, len);
+    } else {
+        val = ~0;
+    }
     return le32_to_cpu(val);
 }
 
-- 
1.6.6.1