block: Fix leak in send_qmp_error_event

ASAN detected a leak when running the ahci-test
/ahci/io/dma/lba28/retry:

Direct leak of 35 byte(s) in 1 object(s) allocated from:
    #0 in malloc
    #1 in __vasprintf_internal
    #2 in vasprintf
    #3 in g_vasprintf
    #4 in g_strdup_vprintf
    #5 in g_strdup_printf
    #6 in object_get_canonical_path ../qom/object.c:2096:19
    #7 in blk_get_attached_dev_id_or_path ../block/block-backend.c:1033:12
    #8 in blk_get_attached_dev_path ../block/block-backend.c:1047:12
    #9 in send_qmp_error_event ../block/block-backend.c:2140:36
    #10 in blk_error_action ../block/block-backend.c:2172:9
    #11 in ide_handle_rw_error ../hw/ide/core.c:875:5
    #12 in ide_dma_cb ../hw/ide/core.c:894:13
    qemu#13 in dma_complete ../system/dma-helpers.c:107:9
    qemu#14 in dma_blk_cb ../system/dma-helpers.c:129:9
    qemu#15 in blk_aio_complete ../block/block-backend.c:1552:9
    qemu#16 in blk_aio_write_entry ../block/block-backend.c:1619:5
    qemu#17 in coroutine_trampoline ../util/coroutine-ucontext.c:175:9

Plug the leak by freeing the device path string.

Signed-off-by: Fabiano Rosas <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-ID: <[email protected]>
[PMD: Use g_autofree]
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>
(cherry picked from commit 23ea425)
Signed-off-by: Michael Tokarev <[email protected]>

Author: Fabiano Rosas

block/block-backend.c

@@ -2134,10 +2134,10 @@ static void send_qmp_error_event(BlockBackend *blk,
 {
     IoOperationType optype;
     BlockDriverState *bs = blk_bs(blk);
+    g_autofree char *path = blk_get_attached_dev_path(blk);
 
     optype = is_read ? IO_OPERATION_TYPE_READ : IO_OPERATION_TYPE_WRITE;
-    qapi_event_send_block_io_error(blk_name(blk),
-                                   blk_get_attached_dev_path(blk),
+    qapi_event_send_block_io_error(blk_name(blk), path,
                                    bs ? bdrv_get_node_name(bs) : NULL, optype,
                                    action, blk_iostatus_is_enabled(blk),
                                    error == ENOSPC, strerror(error));