[PATCH] qtest: do not return freed argument vector from qtest_rsp

[PATCH] qtest: do not return freed argument vector from qtest_rsp

[Paolo Bonzini]

If expected_args is 0, qtest frees the argument vector and then returns it
nevertheless.  Coverity complains; in practice this is not an issue because
expected_args == 0 means that the caller is not interested in the argument
vector, but it would be a potential problem if somebody wanted to add
commands with optional arguments to qtest.

Suggested-by: Kamil Dudka <kdudka@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 tests/qtest/libqtest.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
index be0fb430dd..e49f3a1e45 100644
--- a/tests/qtest/libqtest.c
+++ b/tests/qtest/libqtest.c
@@ -545,6 +545,7 @@ redo:
         }
     } else {
         g_strfreev(words);
+        words = NULL;
     }
 
     return words;
-- 
2.28.0

Re: [PATCH] qtest: do not return freed argument vector from qtest_rsp

[Thomas Huth]

On 20/11/2020 08.31, Paolo Bonzini wrote:
> If expected_args is 0, qtest frees the argument vector and then returns it
> nevertheless.  Coverity complains; in practice this is not an issue because
> expected_args == 0 means that the caller is not interested in the argument
> vector, but it would be a potential problem if somebody wanted to add
> commands with optional arguments to qtest.
> 
> Suggested-by: Kamil Dudka <kdudka@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  tests/qtest/libqtest.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
> index be0fb430dd..e49f3a1e45 100644
> --- a/tests/qtest/libqtest.c
> +++ b/tests/qtest/libqtest.c
> @@ -545,6 +545,7 @@ redo:
>          }
>      } else {
>          g_strfreev(words);
> +        words = NULL;
>      }
>  
>      return words;
> 

Reviewed-by: Thomas Huth <thuth@redhat.com>

Re: [PATCH] qtest: do not return freed argument vector from qtest_rsp

[Markus Armbruster]

Paolo Bonzini <pbonzini@redhat.com> writes:

> If expected_args is 0, qtest frees the argument vector and then returns it
> nevertheless.  Coverity complains; in practice this is not an issue because
> expected_args == 0 means that the caller is not interested in the argument
> vector, but it would be a potential problem if somebody wanted to add
> commands with optional arguments to qtest.
>
> Suggested-by: Kamil Dudka <kdudka@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  tests/qtest/libqtest.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
> index be0fb430dd..e49f3a1e45 100644
> --- a/tests/qtest/libqtest.c
> +++ b/tests/qtest/libqtest.c
> @@ -545,6 +545,7 @@ redo:
       if (expected_args) {
           for (i = 0; i < expected_args; i++) {
               g_assert(words[i] != NULL);
>          }
>      } else {
>          g_strfreev(words);
> +        words = NULL;
>      }
>  
>      return words;

The patch is okay, so

Reviewed-by: Markus Armbruster <armbru@redhat.com>

Odd: we require at least @expected_args, but more is fine.  Not what the
name @expected_args made me expect.

We treat expected_args == 0 as special case to save callers the trouble
to free @words.  Okay, but I'd try a more regular interface:

* one function that takes @expected_args and returns @words, always.

* a simple wrapper around it that passes zero @expected_args and frees
  @words.