[qemu-xen staging] qom: Plug memory leak in "info qom-tree"

[patchbot@xxxxxxx]

commit ab2d185d6b1d3aa1ab2416a896347d235e32ac3d
Author:     Markus Armbruster <armbru@xxxxxxxxxx>
AuthorDate: Tue Jul 14 18:01:59 2020 +0200
Commit:     Thomas Huth <thuth@xxxxxxxxxx>
CommitDate: Fri Jul 17 10:44:23 2020 +0200

    qom: Plug memory leak in "info qom-tree"
    
    Commit e8c9e65816 "qom: Make "info qom-tree" show children sorted"
    created a memory leak, because I didn't realize
    object_get_canonical_path_component()'s value needs to be freed.
    
    Reproducer:
    
        $ qemu-system-x86_64 -nodefaults -display none -S -monitor stdio
        QEMU 5.0.50 monitor - type 'help' for more information
        (qemu) info qom-tree
    
    This leaks some 4500 path components, 12-13 characters on average,
    i.e. roughly 100kBytes depending on the allocator.  A couple of
    hundred "info qom-tree" here, a couple of hundred there, and soon
    enough we're talking about real memory.
    
    Plug the leak.
    
    Fixes: e8c9e65816f5dbfe18ad3b2be938d0d8192d459a
    Signed-off-by: Markus Armbruster <armbru@xxxxxxxxxx>
    Reported-by: Reviewed-by: Li Qiang <liq3ea@xxxxxxxxx> [sent same patch]
    Message-Id: <20200714160202.3121879-3-armbru@xxxxxxxxxx>
    Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
    Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
---
 qom/qom-hmp-cmds.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/qom/qom-hmp-cmds.c b/qom/qom-hmp-cmds.c
index 9ed8bb1c9f..aaacadacca 100644
--- a/qom/qom-hmp-cmds.c
+++ b/qom/qom-hmp-cmds.c
@@ -96,8 +96,10 @@ static void print_qom_composition(Monitor *mon, Object *obj, 
int indent);
 
 static int qom_composition_compare(const void *a, const void *b, void *ignore)
 {
-    return g_strcmp0(a ? object_get_canonical_path_component(a) : NULL,
-                     b ? object_get_canonical_path_component(b) : NULL);
+    g_autofree char *ac = object_get_canonical_path_component(a);
+    g_autofree char *bc = object_get_canonical_path_component(b);
+
+    return g_strcmp0(ac, bc);
 }
 
 static int insert_qom_composition_child(Object *obj, void *opaque)
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#staging