[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH] hw/display/xenfb: Replace unreachable code by abort()



On 29/7/25 14:16, Markus Armbruster wrote:
Philippe Mathieu-Daudé <philmd@xxxxxxxxxx> writes:

On 29/7/25 13:12, Markus Armbruster wrote:
xenfb_mouse_event() has a switch statement whose controlling
expression move->axis is an enum InputAxis.  The enum values are
INPUT_AXIS_X and INPUT_AXIS_Y, encoded as 0 and 1.  The switch has a
case for both axes.  In addition, it has an unreachable default label.
This convinces Coverity that move->axis can be greater than 1.  It
duly reports a buffer overrun when it is used to subscript an array
with two elements.
Replace the unreachable code by abort().
Resolves: Coverity CID 1613906
Signed-off-by: Markus Armbruster <armbru@xxxxxxxxxx>
---
   hw/display/xenfb.c | 3 +--
   1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
index 22822fecea..5e6c691779 100644
--- a/hw/display/xenfb.c
+++ b/hw/display/xenfb.c
@@ -283,8 +283,7 @@ static void xenfb_mouse_event(DeviceState *dev, QemuConsole 
*src,
                   scale = surface_height(surface) - 1;
                   break;
               default:
-                scale = 0x8000;
-                break;
+                abort();

We prefer GLib g_assert_not_reached() over abort() because it displays
the file, line number & function before aborting.

The purpose of this line is to tell the compiler we can't get there,
with the least amount of ceremony.

We have ~600 calls of abort().

And ~1600 of g_assert_not_reached() =)

$ git grep -w 'abort();' | wc -l
     556
$ git grep -w 'g_assert_not_reached();' | wc -l
    1551

Whoever merges this: feel free to replace by g_assert_not_reached().

               }
               xenfb->axis[move->axis] = move->value * scale / 0x7fff;
           }





 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.