Hi there and a happy new year,
I am currently experimenting with OVN VIF plugins and the port creation
process seems to have a minor bug.
Bug Description
---
During writing a custom plugin, I read the docs for the
`vif_plug_port_prepare` function and determined, I should return `false`
in case of the plugin not wanting to create or update a port:
> The VIF plug implementation should return 'true' if it wants the
caller to create/update a port/interface, 'false' otherwise.
When returning `false`, however, I noticed that the ovn-controller
process just dies with a SEGFAULT, regardless of whether I fill a
context or not.
I expected the controller to just spit out a message that the plugin
does not want to do anything but no crash.
Version Information
---
OVN Version: ovn-controller 25.09.0
OVN Commit Hash: 8890abf5a25b7b67f08aca8917c1d00cf2296a56 (but problem
persists with the current HEAD).
Possible Solution
---
In `ovn/controller/vif-plug.c` (see
https://github.com/ovn-org/ovn/blob/3708cf59ea3759152adaa875dbf244e2e4898650/controller/vif-plug.c#L330-L339),
I found that in case of the plugin returning `false` in the
`..._prepare` function, the context is destroyed and
`consider_plug_lport__` returns `true`.
Thus, `consider_plug_lport` accesses the (already destroyed) context and
crashes the controller.
A possible fix would be to return `false` there, too:
```diff
diff --git a/controller/vif-plug.c b/controller/vif-plug.c
index 1fa536cad..06a13c47b 100644
--- a/controller/vif-plug.c
+++ b/controller/vif-plug.c
@@ -336,7 +336,7 @@ consider_plug_lport__(const struct vif_plug_class
*vif_plug,
"plug provider.",
pb->logical_port);
destroy_port_ctx(vif_plug_port_ctx);
- return true;
+ return false;
}
*vif_plug_port_ctx_ptr = vif_plug_port_ctx;
return true;
```
If I am doing something wrong, I am happy to be corrected.
Best regards
Felix
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