[PULL 16/18] hw/audio/virtio-sound: fix heap buffer overflow

[Michael S. Tsirkin]

From: Volker Rümelin <vr_qemu@t-online.de>

Currently, the guest may write to the device configuration space,
whereas the virtio sound device specification in chapter 5.14.4
clearly states that the fields in the device configuration space
are driver-read-only.

Remove the set_config function from the virtio_snd class.

This also prevents a heap buffer overflow. See QEMU issue #2296.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2296
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-Id: <20240901130112.8242-1-vr_qemu@t-online.de>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/audio/virtio-snd.c | 24 ------------------------
 hw/audio/trace-events |  1 -
 2 files changed, 25 deletions(-)

diff --git a/hw/audio/virtio-snd.c b/hw/audio/virtio-snd.c
index d1cf5eb445..69838181dd 100644
--- a/hw/audio/virtio-snd.c
+++ b/hw/audio/virtio-snd.c
@@ -107,29 +107,6 @@ virtio_snd_get_config(VirtIODevice *vdev, uint8_t *config)
 
 }
 
-static void
-virtio_snd_set_config(VirtIODevice *vdev, const uint8_t *config)
-{
-    VirtIOSound *s = VIRTIO_SND(vdev);
-    const virtio_snd_config *sndconfig =
-        (const virtio_snd_config *)config;
-
-
-   trace_virtio_snd_set_config(vdev,
-                               s->snd_conf.jacks,
-                               sndconfig->jacks,
-                               s->snd_conf.streams,
-                               sndconfig->streams,
-                               s->snd_conf.chmaps,
-                               sndconfig->chmaps);
-
-    memcpy(&s->snd_conf, sndconfig, sizeof(virtio_snd_config));
-    le32_to_cpus(&s->snd_conf.jacks);
-    le32_to_cpus(&s->snd_conf.streams);
-    le32_to_cpus(&s->snd_conf.chmaps);
-
-}
-
 static void
 virtio_snd_pcm_buffer_free(VirtIOSoundPCMBuffer *buffer)
 {
@@ -1400,7 +1377,6 @@ static void virtio_snd_class_init(ObjectClass *klass, 
void *data)
     vdc->realize = virtio_snd_realize;
     vdc->unrealize = virtio_snd_unrealize;
     vdc->get_config = virtio_snd_get_config;
-    vdc->set_config = virtio_snd_set_config;
     vdc->get_features = get_features;
     vdc->reset = virtio_snd_reset;
     vdc->legacy_features = 0;
diff --git a/hw/audio/trace-events b/hw/audio/trace-events
index b1870ff224..b8ef572767 100644
--- a/hw/audio/trace-events
+++ b/hw/audio/trace-events
@@ -41,7 +41,6 @@ asc_update_irq(int irq, int a, int b) "set IRQ to %d (A: 0x%x 
B: 0x%x)"
 
 #virtio-snd.c
 virtio_snd_get_config(void *vdev, uint32_t jacks, uint32_t streams, uint32_t 
chmaps) "snd %p: get_config jacks=%"PRIu32" streams=%"PRIu32" chmaps=%"PRIu32""
-virtio_snd_set_config(void *vdev, uint32_t jacks, uint32_t new_jacks, uint32_t 
streams, uint32_t new_streams, uint32_t chmaps, uint32_t new_chmaps) "snd %p: 
set_config jacks from %"PRIu32"->%"PRIu32", streams from %"PRIu32"->%"PRIu32", 
chmaps from %"PRIu32"->%"PRIu32
 virtio_snd_get_features(void *vdev, uint64_t features) "snd %p: get_features 
0x%"PRIx64
 virtio_snd_vm_state_running(void) "vm state running"
 virtio_snd_vm_state_stopped(void) "vm state stopped"
-- 
MST