Re: [PATCH] test-vmstate: fix bad GTree usage, use-after-free

[Auger Eric <eric.auger@redhat.com>]

Hi Marc-Andre

On 8/27/20 6:18 PM, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> According to g_tree_foreach() documentation:
> "The tree may not be modified while iterating over it (you can't
> add/remove items)."

Hum I did not see that.
> 
> Fixes: 9a85e4b8f6 ("migration: Support gtree migration")
> Cc: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  tests/test-vmstate.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/tests/test-vmstate.c b/tests/test-vmstate.c
> index f7b3868881..31aefa78f0 100644
> --- a/tests/test-vmstate.c
> +++ b/tests/test-vmstate.c
> @@ -1078,7 +1078,6 @@ static gboolean diff_tree(gpointer key, gpointer value, gpointer data)
>      struct match_node_data d = {tp->tree2, key, value};
>  
>      g_tree_foreach(tp->tree2, tp->match_node, &d);
> -    g_tree_remove(tp->tree1, key);
it does not test the same thing I am afraid. If one of the trees
contains more elements than the others this won't be detected.

Also there is another case of removal inside the traversal in the
match_node(): in match_interval_mapping_node() and match_domain_node()

Thanks

Eric


>      return false;
>  }
>  
> @@ -1088,7 +1087,7 @@ static void compare_trees(GTree *tree1, GTree *tree2,
>      struct tree_cmp_data tp = {tree1, tree2, function};
>  
>      g_tree_foreach(tree1, diff_tree, &tp);
> -    assert(g_tree_nnodes(tree1) == 0);> +    g_tree_destroy(g_tree_ref(tree1));
>      assert(g_tree_nnodes(tree2) == 0);
>  }
>  
>