migration/multifd: Free MultiFDRecvParams::data

In multifd_recv_setup() we allocate (among other things)
 * a MultiFDRecvData struct to multifd_recv_state::data
 * a MultiFDRecvData struct to each multfd_recv_state->params[i].data

(Then during execution we might swap these pointers around.)

But in multifd_recv_cleanup() we free multifd_recv_state->data
in multifd_recv_cleanup_state() but we don't ever free the
multifd_recv_state->params[i].data. This results in a memory
leak reported by LeakSanitizer:

(cd build/asan && \
   ASAN_OPTIONS="fast_unwind_on_malloc=0:strip_path_prefix=/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/../../" \
   QTEST_QEMU_BINARY=./qemu-system-x86_64 \
   ./tests/qtest/migration-test --tap -k -p /x86_64/migration/multifd/file/mapped-ram )
[...]
Direct leak of 72 byte(s) in 3 object(s) allocated from:
    #0 0x561cc0afcfd8 in __interceptor_calloc (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/qemu-system-x86_64+0x218efd8) (BuildId: be72e086d4e47b172b0a72779972213fd9916466)
    #1 0x7f89d37acc50 in g_malloc0 debian/build/deb/../../../glib/gmem.c:161:13
    #2 0x561cc1e9c83c in multifd_recv_setup migration/multifd.c:1606:19
    #3 0x561cc1e68618 in migration_ioc_process_incoming migration/migration.c:972:9
    #4 0x561cc1e3ac59 in migration_channel_process_incoming migration/channel.c:45:9
    #5 0x561cc1e4fa0b in file_accept_incoming_migration migration/file.c:132:5
    #6 0x561cc30f2c0c in qio_channel_fd_source_dispatch io/channel-watch.c:84:12
    #7 0x7f89d37a3c43 in g_main_dispatch debian/build/deb/../../../glib/gmain.c:3419:28
    #8 0x7f89d37a3c43 in g_main_context_dispatch debian/build/deb/../../../glib/gmain.c:4137:7
    #9 0x561cc3b21659 in glib_pollfds_poll util/main-loop.c:287:9
    #10 0x561cc3b1ff93 in os_host_main_loop_wait util/main-loop.c:310:5
    #11 0x561cc3b1fb5c in main_loop_wait util/main-loop.c:589:11
    #12 0x561cc1da2917 in qemu_main_loop system/runstate.c:801:9
    #13 0x561cc3796c1c in qemu_default_main system/main.c:37:14
    #14 0x561cc3796c67 in main system/main.c:48:12
    #15 0x7f89d163bd8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #16 0x7f89d163be3f in __libc_start_main csu/../csu/libc-start.c:392:3
    #17 0x561cc0a79fa4 in _start (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/qemu-system-x86_64+0x210bfa4) (BuildId: be72e086d4e47b172b0a72779972213fd9916466)

Direct leak of 24 byte(s) in 1 object(s) allocated from:
    #0 0x561cc0afcfd8 in __interceptor_calloc (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/qemu-system-x86_64+0x218efd8) (BuildId: be72e086d4e47b172b0a72779972213fd9916466)
    #1 0x7f89d37acc50 in g_malloc0 debian/build/deb/../../../glib/gmem.c:161:13
    #2 0x561cc1e9bed9 in multifd_recv_setup migration/multifd.c:1588:32
    #3 0x561cc1e68618 in migration_ioc_process_incoming migration/migration.c:972:9
    #4 0x561cc1e3ac59 in migration_channel_process_incoming migration/channel.c:45:9
    #5 0x561cc1e4fa0b in file_accept_incoming_migration migration/file.c:132:5
    #6 0x561cc30f2c0c in qio_channel_fd_source_dispatch io/channel-watch.c:84:12
    #7 0x7f89d37a3c43 in g_main_dispatch debian/build/deb/../../../glib/gmain.c:3419:28
    #8 0x7f89d37a3c43 in g_main_context_dispatch debian/build/deb/../../../glib/gmain.c:4137:7
    #9 0x561cc3b21659 in glib_pollfds_poll util/main-loop.c:287:9
    #10 0x561cc3b1ff93 in os_host_main_loop_wait util/main-loop.c:310:5
    #11 0x561cc3b1fb5c in main_loop_wait util/main-loop.c:589:11
    #12 0x561cc1da2917 in qemu_main_loop system/runstate.c:801:9
    #13 0x561cc3796c1c in qemu_default_main system/main.c:37:14
    #14 0x561cc3796c67 in main system/main.c:48:12
    #15 0x7f89d163bd8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #16 0x7f89d163be3f in __libc_start_main csu/../csu/libc-start.c:392:3
    #17 0x561cc0a79fa4 in _start (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/qemu-system-x86_64+0x210bfa4) (BuildId: be72e086d4e47b172b0a72779972213fd9916466)

SUMMARY: AddressSanitizer: 96 byte(s) leaked in 4 allocation(s).

Free the params[i].data too.

Cc: [email protected]
Fixes: d117ed0 ("migration/multifd: Allow receiving pages without packets")
Signed-off-by: Peter Maydell <[email protected]>
Reviewed-by: Fabiano Rosas <[email protected]>
Signed-off-by: Fabiano Rosas <[email protected]>

migration/multifd.c

@@ -1357,6 +1357,8 @@ static void multifd_recv_cleanup_channel(MultiFDRecvParams *p)
     qemu_mutex_destroy(&p->mutex);
     qemu_sem_destroy(&p->sem_sync);
     qemu_sem_destroy(&p->sem);
+    g_free(p->data);
+    p->data = NULL;
     g_free(p->name);
     p->name = NULL;
     p->packet_len = 0;