Re: [PATCH] io/channel-tls: plug memory leakage on GSource

[Philippe Mathieu-Daudé]

On 7/3/23 00:15, Matheus Tavares Bernardino wrote:
> This leakage can be seen through test-io-channel-tls:
>
> $ ../configure --target-list=aarch64-softmmu --enable-sanitizers
> $ make ./tests/unit/test-io-channel-tls
> $ ./tests/unit/test-io-channel-tls
>
> Indirect leak of 104 byte(s) in 1 object(s) allocated from:
>      #0 0x7f81d1725808 in __interceptor_malloc 
> ../../../../src/libsanitizer/asan/asan_malloc_linux.cc:144
>      #1 0x7f81d135ae98 in g_malloc 
> (/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x57e98)
>      #2 0x55616c5d4c1b in object_new_with_propv ../qom/object.c:795
>      #3 0x55616c5d4a83 in object_new_with_props ../qom/object.c:768
>      #4 0x55616c5c5415 in test_tls_creds_create 
> ../tests/unit/test-io-channel-tls.c:70
>      #5 0x55616c5c5a6b in test_io_channel_tls 
> ../tests/unit/test-io-channel-tls.c:158
>      #6 0x7f81d137d58d  (/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x7a58d)
>
> Indirect leak of 32 byte(s) in 1 object(s) allocated from:
>      #0 0x7f81d1725a06 in __interceptor_calloc 
> ../../../../src/libsanitizer/asan/asan_malloc_linux.cc:153
>      #1 0x7f81d1472a20 in gnutls_dh_params_init 
> (/lib/x86_64-linux-gnu/libgnutls.so.30+0x46a20)
>      #2 0x55616c6485ff in qcrypto_tls_creds_x509_load 
> ../crypto/tlscredsx509.c:634
>      #3 0x55616c648ba2 in qcrypto_tls_creds_x509_complete 
> ../crypto/tlscredsx509.c:694
>      #4 0x55616c5e1fea in user_creatable_complete ../qom/object_interfaces.c:28
>      #5 0x55616c5d4c8c in object_new_with_propv ../qom/object.c:807
>      #6 0x55616c5d4a83 in object_new_with_props ../qom/object.c:768
>      #7 0x55616c5c5415 in test_tls_creds_create 
> ../tests/unit/test-io-channel-tls.c:70
>      #8 0x55616c5c5a6b in test_io_channel_tls 
> ../tests/unit/test-io-channel-tls.c:158
>      #9 0x7f81d137d58d  (/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x7a58d)
>
> ...
>
> SUMMARY: AddressSanitizer: 49143 byte(s) leaked in 184 allocation(s).
>
> The docs for `g_source_add_child_source(source, child_source)` says
> "source will hold a reference on child_source while child_source is
> attached to it." Therefore, we should unreference the child source at
> `qio_channel_tls_read_watch()` after attaching it to `source`. With this
> change, ./tests/unit/test-io-channel-tls shows no leakages.
>
> Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
> ---
>   io/channel-tls.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/io/channel-tls.c b/io/channel-tls.c
> index 8052945ba0..5a7a3d48d6 100644
> --- a/io/channel-tls.c
> +++ b/io/channel-tls.c
> @@ -446,6 +446,7 @@ qio_channel_tls_read_watch(QIOChannelTLS *tioc, GSource 
> *source)
>       object_ref(OBJECT(tioc));
>   
>       g_source_add_child_source(source, child);
> +    g_source_unref(child);

Or declare child with 'g_autoptr(GSource)'. The difference is
only a matter of style, so I'll let Daniel to decide what is
preferred. Regardless:

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

>   }