[{"id":3675464,"web_url":"http://patchwork.ozlabs.org/comment/3675464/","msgid":"","list_archive_url":null,"date":"2026-04-09T18:52:48","subject":"Re: [PATCH v2 1/2] migration/vmstate: Add VMState support for\n GByteArray","submitter":{"id":66774,"url":"http://patchwork.ozlabs.org/api/people/66774/","name":"Marc-André Lureau","email":"marcandre.lureau@redhat.com"},"content":"On Thu, Apr 9, 2026 at 9:52 PM Arun Menon wrote:\n>\n> From: Arun Menon \n>\n> In GLib, GByteArray is an object managed by the library. Currently,\n> migrating a GByteArray requires treating it as a raw C struct and using\n> VMSTATE_VBUFFER_ALLOC_UINT32. For example, see vmstate_vdba in\n> ui/vdagent.c\n>\n> QEMU cannot pretend that GByteArray is a C struct and simply use\n> VMS_ALLOC to g_malloc() the buffer. This is because, VMS_ALLOC blindly\n> overwrites the data pointer with a newly allocated buffer, thereby\n> leaking the previous memory. Besides, GLib tracks the array's capacity\n> in a hidden alloc field. Bypassing GLib APIs leave this capacity out of\n> sync with the newly allocated buffer, potentially leading to heap buffer\n> overflows during subsequent g_byte_array_append() calls.\n>\n> This commit introduces VMSTATE_GBYTEARRAY which uses specific library\n> API calls (g_byte_array_set_size()) to safely resize and populate the\n> buffer.\n>\n> Signed-off-by: Arun Menon \n> Fix-Suggested-by: Marc-André Lureau \n> Signed-off-by: Arun Menon \n\nyou have 2 signed-off trailer tags\n\n> ---\n> include/migration/vmstate.h | 10 ++++++++++\n> migration/vmstate-types.c | 37 +++++++++++++++++++++++++++++++++++++\n> 2 files changed, 47 insertions(+)\n>\n> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h\n> index 62c2abd0c4..f503a40ec0 100644\n> --- a/include/migration/vmstate.h\n> +++ b/include/migration/vmstate.h\n> @@ -265,6 +265,7 @@ extern const VMStateInfo vmstate_info_bitmap;\n> extern const VMStateInfo vmstate_info_qtailq;\n> extern const VMStateInfo vmstate_info_gtree;\n> extern const VMStateInfo vmstate_info_qlist;\n> +extern const VMStateInfo vmstate_info_g_byte_array;\n>\n> #define type_check_2darray(t1,t2,n,m) ((t1(*)[n][m])0 - (t2*)0)\n> /*\n> @@ -892,6 +893,15 @@ extern const VMStateInfo vmstate_info_qlist;\n> .start = offsetof(_type, _next), \\\n> }\n>\n> +#define VMSTATE_GBYTEARRAY(_field, _state, _version) { \\\n> + .name = (stringify(_field)), \\\n> + .version_id = (_version), \\\n> + .size = sizeof(GByteArray), \\\n> + .info = &vmstate_info_g_byte_array, \\\n> + .flags = VMS_SINGLE, \\\n> + .offset = vmstate_offset_pointer(_state, _field, GByteArray), \\\n> +}\n> +\n> /* _f : field name\n> _f_n : num of elements field_name\n> _n : num of elements\n> diff --git a/migration/vmstate-types.c b/migration/vmstate-types.c\n> index 89cb211472..743c2092e9 100644\n> --- a/migration/vmstate-types.c\n> +++ b/migration/vmstate-types.c\n> @@ -942,3 +942,40 @@ const VMStateInfo vmstate_info_qlist = {\n> .get = get_qlist,\n> .put = put_qlist,\n> };\n> +\n> +static int get_g_byte_array(QEMUFile *f, void *pv, size_t size,\n> + const VMStateField *field)\n> +{\n> + GByteArray **byte_array = (GByteArray **)pv;\n> + uint32_t len = qemu_get_be32(f);\n> +\n> + if (*byte_array == NULL) {\n> + *byte_array = g_byte_array_new();\n> + }\n> +\n> + g_byte_array_set_size(*byte_array, len);\n> + if (len > 0) {\n> + qemu_get_buffer(f, (*byte_array)->data, len);\n> + }\n> + return 0;\n> +}\n> +\n> +static int put_g_byte_array(QEMUFile *f, void *pv, size_t size,\n> + const VMStateField *field, JSONWriter *vmdesc)\n> +{\n> + GByteArray *byte_array = *(GByteArray **)pv;\n> + uint32_t len = byte_array ? byte_array->len : 0;\n> +\n> + qemu_put_be32(f, len);\n> + if (len > 0) {\n> + qemu_put_buffer(f, byte_array->data, len);\n> + }\n> +\n> + return 0;\n> +}\n> +\n> +const VMStateInfo vmstate_info_g_byte_array = {\n> + .name = \"GByteArray\",\n> + .get = get_g_byte_array,\n> + .put = put_g_byte_array,\n> +};\n> --\n> 2.53.0\n>\n\nthe \"if (len>0)\" may be superflous, but ok\n\nReviewed-by: Marc-André Lureau ","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=DHLoHm9i;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=google header.b=dyvqIu+D;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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