vty: fix use-after-free and memleaks in is_cmd_ambiguous()
vty_test: add test against ambiguous cmd causing use-after-free and memory
leaks. Add this test along with the fix, because the new test triggers the
memory use-after-free and leaks, causing build failures.
Add cmd_deopt_with_ctx() to allow passing a specific talloc ctx.
is_cmd_ambiguous(): keep all cmd_deopt() allocations until the function exits.
Add a comment explaining why. Before this, if a command matched an optional
"[arg]" with square brackets, we would keep it in local var 'matched', but we
would free the string it points to at the end of that loop iteration; upon
encountering another match, we would attempt to strcmp against the freed
'matched'. Instead of adding hard-to-read and -verify free/alloc dances to keep
the 'matched' accurately freed/non-freed/..., just keep all cmd_deopt() string
allocated until done.
Needless to say that this should have been implemented on a lower level upon
inventing optional args, but at least this is fixing a program crash.
Related: OS#33903390
Change-Id: Ia71ba742108b5ff020997bfb612ad5eb30d04fcd
diff --git a/tests/vty/vty_test.ok b/tests/vty/vty_test.ok
index bd6c5d6..2f76ff9 100644
--- a/tests/vty/vty_test.ok
+++ b/tests/vty/vty_test.ok
@@ -286,4 +286,23 @@
called level3 node k
called level1 child cmd k
got rc=0
+Going to test is_cmd_ambiguous()
+Going to execute 'ambiguous_nr'
+Called: 'ambiguous_nr [<0-23>]' (argc=0)
+Returned: 0, Current node: 1 '%s> '
+Going to execute 'ambiguous_nr 23'
+Called: 'ambiguous_nr [<0-23>]' (argc=1)
+Returned: 0, Current node: 1 '%s> '
+Going to execute 'ambiguous_nr 23 keyword'
+Called: 'ambiguous_nr <0-23> keyword'
+Returned: 0, Current node: 1 '%s> '
+Going to execute 'ambiguous_str'
+Called: 'ambiguous_str [ARG]' (argc=0)
+Returned: 0, Current node: 1 '%s> '
+Going to execute 'ambiguous_str arg'
+Called: 'ambiguous_str [ARG]' (argc=1)
+Returned: 0, Current node: 1 '%s> '
+Going to execute 'ambiguous_str arg keyword'
+Called: 'ambiguous_str ARG keyword'
+Returned: 0, Current node: 1 '%s> '
All tests passed