On 6/24/21 4:44 AM, Qiang Liu wrote:
> The I/O sampling rate range is enforced to 5000 to 45000HZ according to
> commit a2cd86a9. Setting I/O sampling rate with command 41h/42h, a guest
> user can break this assumption and trigger an assertion in audio_calloc
> via command 0xd4. This patch restricts the I/O sampling rate range for
> command 41h/42h.
>
> Fixes: 85571bc7415 ("audio merge (malc)")
> Signed-off-by: Qiang Liu <cyruscy...@gmail.com>
> ---
> hw/audio/sb16.c | 31 +++++++++++++++++++------------
> tests/qtest/fuzz-sb16-test.c | 17 +++++++++++++++++
> 2 files changed, 36 insertions(+), 12 deletions(-)
>
> diff --git a/hw/audio/sb16.c b/hw/audio/sb16.c
> index 5cf121f..60f1f75 100644
> --- a/hw/audio/sb16.c
> +++ b/hw/audio/sb16.c
> @@ -229,6 +229,23 @@ static void continue_dma8 (SB16State *s)
> control (s, 1);
> }
>
> +static inline int restrict_sampling_rate(int freq)
No need to 'inline', 1/ this is not performance critical code
path, and 2/ we expect the compiler to be clever enough to figure
that by itself.
> +{
> + if (freq < SAMPLE_RATE_MIN) {
> + qemu_log_mask(LOG_GUEST_ERROR,
> + "sampling range too low: %d, increasing to %u\n",
> + freq, SAMPLE_RATE_MIN);
> + return SAMPLE_RATE_MIN;
> + } else if (freq > SAMPLE_RATE_MAX) {
> + qemu_log_mask(LOG_GUEST_ERROR,
> + "sampling range too high: %d, decreasing to %u\n",
> + freq, SAMPLE_RATE_MAX);
> + return SAMPLE_RATE_MAX;
> + } else {
> + return freq;
> + }
> +}
> +
> static void dma_cmd8 (SB16State *s, int mask, int dma_len)
> {
> s->fmt = AUDIO_FORMAT_U8;
> @@ -244,17 +261,7 @@ static void dma_cmd8 (SB16State *s, int mask, int
> dma_len)
> int tmp = (256 - s->time_const);
> s->freq = (1000000 + (tmp / 2)) / tmp;
> }
> - if (s->freq < SAMPLE_RATE_MIN) {
> - qemu_log_mask(LOG_GUEST_ERROR,
> - "sampling range too low: %d, increasing to %u\n",
> - s->freq, SAMPLE_RATE_MIN);
> - s->freq = SAMPLE_RATE_MIN;
> - } else if (s->freq > SAMPLE_RATE_MAX) {
> - qemu_log_mask(LOG_GUEST_ERROR,
> - "sampling range too high: %d, decreasing to %u\n",
> - s->freq, SAMPLE_RATE_MAX);
> - s->freq = SAMPLE_RATE_MAX;
> - }
> + s->freq = restrict_sampling_rate(s->freq);
>
> if (dma_len != -1) {
> s->block_size = dma_len << s->fmt_stereo;
> @@ -768,7 +775,7 @@ static void complete (SB16State *s)
> * and FT2 sets output freq with this (go figure). Compare:
> *
> http://homepages.cae.wisc.edu/~brodskye/sb16doc/sb16doc.html#SamplingRate
> */
> - s->freq = dsp_get_hilo (s);
> + s->freq = restrict_sampling_rate(dsp_get_hilo(s));
It seems the best we can do here...
Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
> ldebug ("set freq %d\n", s->freq);
> break;
Thanks for the fix,
Phil.
