From: Manos Pitsidianakis <manos.pitsidiana...@linaro.org> When reading input audio in the virtio-snd input callback, virtio_snd_pcm_in_cb(), we do not check whether the iov can actually fit the data buffer. This is because we use the buffer->size field as a total-so-far accumulator instead of byte-size-left like in TX buffers.
This triggers an out of bounds write if the size of the virtio queue element is equal to virtio_snd_pcm_status, which makes the available space for audio data zero. This commit adds a check for reaching the maximum buffer size before attempting any writes. Reported-by: Zheyu Ma <zheyum...@gmail.com> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2427 Signed-off-by: Manos Pitsidianakis <manos.pitsidiana...@linaro.org> Message-Id: <virtio-snd-fuzz-2427-fix-v1-manos.pitsidiana...@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org> Reviewed-by: Michael S. Tsirkin <m...@redhat.com> Signed-off-by: Michael S. Tsirkin <m...@redhat.com> (cherry picked from commit 98e77e3dd8dd6e7aa9a7dffa60f49c8c8a49d4e3) Signed-off-by: Michael Tokarev <m...@tls.msk.ru> diff --git a/hw/audio/virtio-snd.c b/hw/audio/virtio-snd.c index 092ba2302b..4d15fe0e31 100644 --- a/hw/audio/virtio-snd.c +++ b/hw/audio/virtio-snd.c @@ -1261,7 +1261,7 @@ static void virtio_snd_pcm_in_cb(void *data, int available) { VirtIOSoundPCMStream *stream = data; VirtIOSoundPCMBuffer *buffer; - size_t size; + size_t size, max_size; WITH_QEMU_LOCK_GUARD(&stream->queue_mutex) { while (!QSIMPLEQ_EMPTY(&stream->queue)) { @@ -1275,7 +1275,12 @@ static void virtio_snd_pcm_in_cb(void *data, int available) continue; } + max_size = iov_size(buffer->elem->in_sg, buffer->elem->in_num); for (;;) { + if (buffer->size >= max_size) { + return_rx_buffer(stream, buffer); + break; + } size = AUD_read(stream->voice.in, buffer->data + buffer->size, MIN(available, (stream->params.period_bytes - -- 2.39.2
