In the Linux kernel, the following vulnerability has been resolved: ALSA: firewire: isight: bound the sample count to the packet payload i

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.

 1count = be32_to_cpu(payload->sample_count);
 2if (likely(count <= (length - 16) / 4))
 3	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.