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{ciqlts9_2} ALSA: usb-audio: Fix out of bounds reads when finding clock sources #241

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Merged
merged 1 commit into from
May 2, 2025
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{ciqlts9_2} ALSA: usb-audio: Fix out of bounds reads when finding clock sources #241

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24 changes: 23 additions & 1 deletion sound/usb/clock.c
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,12 @@ union uac23_clock_multiplier_desc {
struct uac_clock_multiplier_descriptor v3;
};

/* check whether the descriptor bLength has the minimal length */
#define DESC_LENGTH_CHECK(p, proto) \
((proto) == UAC_VERSION_3 ? \
((p)->v3.bLength >= sizeof((p)->v3)) : \
((p)->v2.bLength >= sizeof((p)->v2)))

#define GET_VAL(p, proto, field) \
((proto) == UAC_VERSION_3 ? (p)->v3.field : (p)->v2.field)

Expand All @@ -58,20 +64,36 @@ static bool validate_clock_source(void *p, int id, int proto)
{
union uac23_clock_source_desc *cs = p;

if (!DESC_LENGTH_CHECK(cs, proto))
return false;
return GET_VAL(cs, proto, bClockID) == id;
}

static bool validate_clock_selector(void *p, int id, int proto)
{
union uac23_clock_selector_desc *cs = p;

return GET_VAL(cs, proto, bClockID) == id;
if (!DESC_LENGTH_CHECK(cs, proto))
return false;
if (GET_VAL(cs, proto, bClockID) != id)
return false;
/* additional length check for baCSourceID array (in bNrInPins size)
* and two more fields (which sizes depend on the protocol)
*/
if (proto == UAC_VERSION_3)
return cs->v3.bLength >= sizeof(cs->v3) + cs->v3.bNrInPins +
4 /* bmControls */ + 2 /* wCSelectorDescrStr */;
else
return cs->v2.bLength >= sizeof(cs->v2) + cs->v2.bNrInPins +
1 /* bmControls */ + 1 /* iClockSelector */;
}

static bool validate_clock_multiplier(void *p, int id, int proto)
{
union uac23_clock_multiplier_desc *cs = p;

if (!DESC_LENGTH_CHECK(cs, proto))
return false;
return GET_VAL(cs, proto, bClockID) == id;
}

Expand Down