In the Linux kernel, the following vulnerability has been resolved:
ALSA: firewire: isight: bound the sample count to the packet payload
isight_packet() takes the frame count from the device iso packet and checks it only against the device claimed iso length.
count = be32_to_cpu(payload->sample_count); if (likely(count <= (length - 16) / 4)) isight_samples(isight, payload->samples, count);
length is the iso header data_length. It can be up to 0xffff. So the gate allows a count up to about 16379. isight_samples() then copies count frames out of payload->samples into the PCM DMA buffer.
payload->samples holds only 2 * MAX_FRAMES_PER_PACKET values. The device multiplexes two samples per frame. A count past MAX_FRAMES_PER_PACKET reads past the payload. A count past the buffer size writes past runtime->dma_area. The smallest PCM buffer is larger than MAX_FRAMES_PER_PACKET. Bounding the count to MAX_FRAMES_PER_PACKET keeps both the read and the write in range.
A malicious or faulty Apple iSight on the FireWire bus reaches this during a normal capture.
Add the MAX_FRAMES_PER_PACKET bound to the gate.
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