From: John Keeping john@metanate.com
[ Upstream commit f2f69bf65df12176843ca11eab99949ba69e128b ]
If bInterval is 1, then p_interval is 8000 and p_interval_mil is 8E9, which is too big for a 32-bit value. While the storage is indeed 64-bit, this value is used as the divisor in do_div() which will truncate it into a uint32_t leading to incorrect calculated values.
Switch back to keeping the base value in struct snd_uac_chip which fits easily into an int, meaning that the division can be done in two steps with the divisor fitting safely into a uint32_t on both steps.
Fixes: 6fec018a7e70 ("usb: gadget: u_audio.c: Adding Playback Pitch ctl for sync playback") Tested-by: Pavel Hofman pavel.hofman@ivitera.com Signed-off-by: John Keeping john@metanate.com Link: https://lore.kernel.org/r/20220104183243.718258-1-john@metanate.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/usb/gadget/function/u_audio.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c index c46400be54641..4fb05f9576a67 100644 --- a/drivers/usb/gadget/function/u_audio.c +++ b/drivers/usb/gadget/function/u_audio.c @@ -76,8 +76,8 @@ struct snd_uac_chip { struct snd_pcm *pcm;
/* pre-calculated values for playback iso completion */ - unsigned long long p_interval_mil; unsigned long long p_residue_mil; + unsigned int p_interval; unsigned int p_framesize; };
@@ -194,21 +194,24 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req) * If there is a residue from this division, add it to the * residue accumulator. */ + unsigned long long p_interval_mil = uac->p_interval * 1000000ULL; + pitched_rate_mil = (unsigned long long) params->p_srate * prm->pitch; div_result = pitched_rate_mil; - do_div(div_result, uac->p_interval_mil); + do_div(div_result, uac->p_interval); + do_div(div_result, 1000000); frames = (unsigned int) div_result;
pr_debug("p_srate %d, pitch %d, interval_mil %llu, frames %d\n", - params->p_srate, prm->pitch, uac->p_interval_mil, frames); + params->p_srate, prm->pitch, p_interval_mil, frames);
p_pktsize = min_t(unsigned int, uac->p_framesize * frames, ep->maxpacket);
if (p_pktsize < ep->maxpacket) { - residue_frames_mil = pitched_rate_mil - frames * uac->p_interval_mil; + residue_frames_mil = pitched_rate_mil - frames * p_interval_mil; p_pktsize_residue_mil = uac->p_framesize * residue_frames_mil; } else p_pktsize_residue_mil = 0; @@ -222,11 +225,11 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req) * size and decrease the accumulator. */ div_result = uac->p_residue_mil; - do_div(div_result, uac->p_interval_mil); + do_div(div_result, uac->p_interval); + do_div(div_result, 1000000); if ((unsigned int) div_result >= uac->p_framesize) { req->length += uac->p_framesize; - uac->p_residue_mil -= uac->p_framesize * - uac->p_interval_mil; + uac->p_residue_mil -= uac->p_framesize * p_interval_mil; pr_debug("increased req length to %d\n", req->length); } pr_debug("remains uac->p_residue_mil %llu\n", uac->p_residue_mil); @@ -591,7 +594,7 @@ int u_audio_start_playback(struct g_audio *audio_dev) unsigned int factor; const struct usb_endpoint_descriptor *ep_desc; int req_len, i; - unsigned int p_interval, p_pktsize; + unsigned int p_pktsize;
ep = audio_dev->in_ep; prm = &uac->p_prm; @@ -612,11 +615,10 @@ int u_audio_start_playback(struct g_audio *audio_dev) /* pre-compute some values for iso_complete() */ uac->p_framesize = params->p_ssize * num_channels(params->p_chmask); - p_interval = factor / (1 << (ep_desc->bInterval - 1)); - uac->p_interval_mil = (unsigned long long) p_interval * 1000000; + uac->p_interval = factor / (1 << (ep_desc->bInterval - 1)); p_pktsize = min_t(unsigned int, uac->p_framesize * - (params->p_srate / p_interval), + (params->p_srate / uac->p_interval), ep->maxpacket);
req_len = p_pktsize;