diff options
| author | Volker Rümelin <vr_qemu@t-online.de> | 2023-11-05 18:25:51 +0100 |
|---|---|---|
| committer | Michael Tokarev <mjt@tls.msk.ru> | 2023-12-20 19:11:10 +0300 |
| commit | a7a2570f22beefcd10e0c58bf65917243cb4ef61 (patch) | |
| tree | 7fb3e4def75c47df00ae78f0100a311d5b45fcd8 /hw | |
| parent | a386866a8dd3c0e79deffbfe269cb40e2e34c665 (diff) | |
hw/audio/hda-codec: fix multiplication overflow
After a relatively short time, there is an multiplication overflow
when multiplying (now - buft_start) with hda_bytes_per_second().
While the uptime now - buft_start only overflows after 2**63 ns
= 292.27 years, this happens hda_bytes_per_second() times faster
with the multiplication. At 44100 samples/s * 2 channels
* 2 bytes/channel = 176400 bytes/s that is 14.52 hours. After the
multiplication overflow the affected audio stream stalls.
Replace the multiplication and following division with muldiv64()
to prevent a multiplication overflow.
Fixes: 280c1e1cdb ("audio/hda: create millisecond timers that handle IO")
Reported-by: M_O_Bz <m_o_bz@163.com>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-Id: <20231105172552.8405-1-vr_qemu@t-online.de>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 74e8593e7e51d6b11ae9c56a3f4e7bb714bac4ec)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Diffstat (limited to 'hw')
| -rw-r--r-- | hw/audio/hda-codec.c | 29 |
1 files changed, 21 insertions, 8 deletions
diff --git a/hw/audio/hda-codec.c b/hw/audio/hda-codec.c index feb8f9e2bb..0f66754b6a 100644 --- a/hw/audio/hda-codec.c +++ b/hw/audio/hda-codec.c @@ -22,6 +22,7 @@ #include "hw/qdev-properties.h" #include "intel-hda.h" #include "migration/vmstate.h" +#include "qemu/host-utils.h" #include "qemu/module.h" #include "intel-hda-defs.h" #include "audio/audio.h" @@ -190,9 +191,9 @@ struct HDAAudioState { bool use_timer; }; -static inline int64_t hda_bytes_per_second(HDAAudioStream *st) +static inline uint32_t hda_bytes_per_second(HDAAudioStream *st) { - return 2LL * st->as.nchannels * st->as.freq; + return 2 * (uint32_t)st->as.nchannels * (uint32_t)st->as.freq; } static inline void hda_timer_sync_adjust(HDAAudioStream *st, int64_t target_pos) @@ -223,12 +224,18 @@ static void hda_audio_input_timer(void *opaque) int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - int64_t buft_start = st->buft_start; + int64_t uptime = now - st->buft_start; int64_t wpos = st->wpos; int64_t rpos = st->rpos; + int64_t wanted_rpos; - int64_t wanted_rpos = hda_bytes_per_second(st) * (now - buft_start) - / NANOSECONDS_PER_SECOND; + if (uptime <= 0) { + /* wanted_rpos <= 0 */ + goto out_timer; + } + + wanted_rpos = muldiv64(uptime, hda_bytes_per_second(st), + NANOSECONDS_PER_SECOND); wanted_rpos &= -4; /* IMPORTANT! clip to frames */ if (wanted_rpos <= rpos) { @@ -287,12 +294,18 @@ static void hda_audio_output_timer(void *opaque) int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - int64_t buft_start = st->buft_start; + int64_t uptime = now - st->buft_start; int64_t wpos = st->wpos; int64_t rpos = st->rpos; + int64_t wanted_wpos; + + if (uptime <= 0) { + /* wanted_wpos <= 0 */ + goto out_timer; + } - int64_t wanted_wpos = hda_bytes_per_second(st) * (now - buft_start) - / NANOSECONDS_PER_SECOND; + wanted_wpos = muldiv64(uptime, hda_bytes_per_second(st), + NANOSECONDS_PER_SECOND); wanted_wpos &= -4; /* IMPORTANT! clip to frames */ if (wanted_wpos <= wpos) { |