Re: [PATCH] hmp: fix memory leak in qom_composition_compare()

[Philippe Mathieu-Daudé]

On 7/14/20 5:11 PM, Li Qiang wrote:
> While 'make chekc', I got following error:
> 
> root@ubuntu:~/qemu# ./tests/qtest/device-introspect-test
> /x86_64/device/introspect/list: OK
> /x86_64/device/introspect/list-fields: OK
> /x86_64/device/introspect/none:
> =================================================================
> ==53741==ERROR: LeakSanitizer: detected memory leaks
> 
> Direct leak of 212 byte(s) in 20 object(s) allocated from:
>     #0 0x7f3b6319cb40 in __interceptor_malloc 
> (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xdeb40)
>     #1 0x7f3b62805ab8 in g_malloc 
> (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x51ab8)
> 
> SUMMARY: AddressSanitizer: 212 byte(s) leaked in 20 allocation(s).
> tests/qtest/libqtest.c:166: kill_qemu() tried to terminate QEMU process but 
> encountered exit status 1 (expected 0)
> Aborted (core dumped)
> 
> This is because the 'info qom-tree' path has a memory leak and qemu
> exit 1. The leak is in 'qom_composition_compare'. This patch fixes this.
> 
> Fixes: e8c9e65816f("qom: Make "info qom-tree" show children sorted")
> Signed-off-by: Li Qiang <liq3ea@163.com>
> ---
>  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..3547d5ba4e 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 *t1 = a ? object_get_canonical_path_component(a) : NULL;
> +    g_autofree char *t2 = b ? object_get_canonical_path_component(b) : NULL;
> +
> +    return g_strcmp0(t1, t2);
>  }
>  
>  static int insert_qom_composition_child(Object *obj, void *opaque)
> 

Ah you won the race with Markus:
https://lists.gnu.org/archive/html/qemu-devel/2020-07/msg04740.html

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>