{"id":2227279,"url":"http://patchwork.ozlabs.org/api/covers/2227279/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/cover/20260423105733.113046-1-armenon@redhat.com/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260423105733.113046-1-armenon@redhat.com>","list_archive_url":null,"date":"2026-04-23T10:57:31","name":"[v4,0/2] migration/vmstate: Add VMState support to safely migrate GByteArray","submitter":{"id":91136,"url":"http://patchwork.ozlabs.org/api/people/91136/?format=json","name":"Arun Menon","email":"armenon@redhat.com"},"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/cover/20260423105733.113046-1-armenon@redhat.com/mbox/","series":[{"id":501181,"url":"http://patchwork.ozlabs.org/api/series/501181/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=501181","date":"2026-04-23T10:57:32","name":"migration/vmstate: Add VMState support to safely migrate GByteArray","version":4,"mbox":"http://patchwork.ozlabs.org/series/501181/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/covers/2227279/comments/","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=CLp6Sk2G;\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=hcTUVlLZ;\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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charset=\"utf-8\"","Content-Transfer-Encoding":"8bit","Received-SPF":"pass client-ip=170.10.133.124; envelope-from=armenon@redhat.com;\n helo=us-smtp-delivery-124.mimecast.com","X-Spam_score_int":"-20","X-Spam_score":"-2.1","X-Spam_bar":"--","X-Spam_report":"(-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001,\n SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"In GLib, GByteArray is an object managed by the library. Currently,\nmigrating a GByteArray requires treating it as a raw C struct and using\nVMSTATE_VBUFFER_ALLOC_UINT32. For example, see vmstate_vdba in\nui/vdagent.c\n\nQEMU cannot pretend that GByteArray is a C struct and simply use\nVMS_ALLOC to g_malloc() the buffer. This is because, VMS_ALLOC blindly\noverwrites the data pointer with a newly allocated buffer, thereby\nleaking the previous memory. Besides, GLib tracks the array's capacity\nin a hidden alloc field. Bypassing GLib APIs leave this capacity out of\nsync with the newly allocated buffer, potentially leading to heap buffer\noverflows during subsequent g_byte_array_append() calls.\n\nThis series adds a new VMState called VMSTATE_GBYTEARRAY, which will\ndirectly use GLib library API calls to create, or resize the object.\nThis is then used in ui/vdaagent.c replacing the use of\nVMSTATE_VBUFFER_ALLOC_UINT32.\n\nChanges in v4:\n- Applied Peter Xu's feedback: unwrapped GByteArray pointer immediately.\n- Removed redundant assert() and ternary logic.\n- Removed unneeded len>0 check around qemu_get_buffer and\n qemu_put_buffer.\n\nChanges in v3:\n- Add assert() checks to get and put functions to prevent NULL pointer\n dereferences, as suggested by Peter Xu.\n\nChanges in v2:\n- Marc-André pointed out the problem of not updating the device state\n itself. To do that we should essentially pass a pointer to the\n GByteArray pointer. Remove VMS_POINTER from VMSTATE_GBYTEARRAY. This\n changes 'pv' to be the address of the pointer field (GByteArray **)\n instead of the pointer's value.\n- Update get_g_byte_array and put_g_byte_array to handle this additional\n level of indirection, allowing safe allocation and updating device state.\n- Link to v1: https://lore.kernel.org/all/20260406115247.4879-1-armenon@redhat.com/\n\nArun Menon (2):\n migration/vmstate: Add VMState support for GByteArray\n ui/vdagent: Use VMSTATE_GBYTEARRAY to safely migrate outbuf\n\n include/migration/vmstate.h | 10 ++++++++++\n migration/vmstate-types.c | 28 ++++++++++++++++++++++++++++\n ui/vdagent.c | 13 +------------\n 3 files changed, 39 insertions(+), 12 deletions(-)"}