[Qemu-devel] [PATCH] hw/i386/pc: fix possible segment fault for port92_write

[liguang]

e.g.
$qemu-system-x86_64 -device port92
will report segment fault,
for port92_write try a un-allocated
assignment for a20_out.
so check before this assignment.

Signed-off-by: liguang <address@hidden>
---
 hw/i386/pc.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index ed7d9ba..a0e8ee0 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -440,7 +440,8 @@ static void port92_write(void *opaque, hwaddr addr, 
uint64_t val,
 
     DPRINTF("port92: write 0x%02x\n", val);
     s->outport = val;
-    qemu_set_irq(*s->a20_out, (val >> 1) & 1);
+    if (s->a20_out)
+        qemu_set_irq(*s->a20_out, (val >> 1) & 1);
     if (val & 1) {
         qemu_system_reset_request();
     }
-- 
1.7.2.5