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ALSA: usb-mixer: us16x08: validate meter packet indices

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get_meter_levels_from_urb() parses the 64-byte meter packets sent by
the device and fills the per-channel arrays meter_level[],
comp_level[] and master_level[] in struct snd_us16x08_meter_store.

Currently the function derives the channel index directly from the
meter packet (MUB2(meter_urb, s) - 1) and uses it to index those
arrays without validating the range. If the packet contains a
negative or out-of-range channel number, the driver may write past
the end of these arrays.

Introduce a local channel variable and validate it before updating the
arrays. We reject negative indices, limit meter_level[] and
comp_level[] to SND_US16X08_MAX_CHANNELS, and guard master_level[]
updates with ARRAY_SIZE(master_level).

Fixes: d2bb390a20 ("ALSA: usb-audio: Tascam US-16x08 DSP mixer quirk")
Reported-by: DARKNAVY (@DarkNavyOrg) <vr@darknavy.com>
Closes: https://lore.kernel.org/tencent_21C112743C44C1A2517FF219@qq.com
Signed-off-by: Shipei Qu <qu@darknavy.com>
Link: https://patch.msgid.link/20251217024630.59576-1-qu@darknavy.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Shipei Qu
2025-12-17 10:46:30 +08:00
committed by Takashi Iwai
parent 5032347c04
commit 5526c1c6ba
1 changed files with 14 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
sound/usb/mixer_us16x08.c
View File

@@ -655,17 +655,25 @@ static void get_meter_levels_from_urb(int s,
u8 *meter_urb)
{
int val = MUC2(meter_urb, s) + (MUC3(meter_urb, s) << 8);
int ch = MUB2(meter_urb, s) - 1;
if (ch < 0)
return;
if (MUA0(meter_urb, s) == 0x61 && MUA1(meter_urb, s) == 0x02 &&
MUA2(meter_urb, s) == 0x04 && MUB0(meter_urb, s) == 0x62) {
if (MUC0(meter_urb, s) == 0x72)
store->meter_level[MUB2(meter_urb, s) - 1] = val;
if (MUC0(meter_urb, s) == 0xb2)
store->comp_level[MUB2(meter_urb, s) - 1] = val;
if (ch < SND_US16X08_MAX_CHANNELS) {
if (MUC0(meter_urb, s) == 0x72)
store->meter_level[ch] = val;
if (MUC0(meter_urb, s) == 0xb2)
store->comp_level[ch] = val;
}
}
if (MUA0(meter_urb, s) == 0x61 && MUA1(meter_urb, s) == 0x02 &&
MUA2(meter_urb, s) == 0x02 && MUB0(meter_urb, s) == 0x62)
store->master_level[MUB2(meter_urb, s) - 1] = val;
MUA2(meter_urb, s) == 0x02 && MUB0(meter_urb, s) == 0x62) {
if (ch < ARRAY_SIZE(store->master_level))
store->master_level[ch] = val;
}
}
/* Function to retrieve current meter values from the device.