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Commit 8866f405 authored by Xi Wang's avatar Xi Wang Committed by Takashi Iwai
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ALSA: usb-audio: avoid integer overflow in create_fixed_stream_quirk() 



A malicious USB device could feed in a large nr_rates value.  This would
cause the subsequent call to kmemdup() to allocate a smaller buffer than
expected, leading to out-of-bounds access.

This patch validates the nr_rates value and reuses the limit introduced
in commit 4fa0e81b ("ALSA: usb-audio: fix possible hang and overflow
in parse_uac2_sample_rate_range()").

Signed-off-by: default avatarXi Wang <xi.wang@gmail.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 27c3afe6

sound/usb/card.h

+1 −0
Original line number Diff line number Diff line 
#ifndef __USBAUDIO_CARD_H

#define __USBAUDIO_CARD_H



#define MAX_NR_RATES	1024

#define MAX_PACKS	20

#define MAX_PACKS_HS	(MAX_PACKS * 8)	/* in high speed mode */

#define MAX_URBS	8

sound/usb/format.c

+1 −3
Original line number Diff line number Diff line
@@ -209,8 +209,6 @@ static int parse_audio_format_rates_v1(struct snd_usb_audio *chip, struct audiof 
	return 0;

}



#define MAX_UAC2_NR_RATES 1024



/*

 * Helper function to walk the array of sample rate triplets reported by

 * the device. The problem is that we need to parse whole array first to
@@ -255,7 +253,7 @@ static int parse_uac2_sample_rate_range(struct audioformat *fp, int nr_triplets, 
			fp->rates |= snd_pcm_rate_to_rate_bit(rate);



			nr_rates++;

			if (nr_rates >= MAX_UAC2_NR_RATES) {

			if (nr_rates >= MAX_NR_RATES) {

				snd_printk(KERN_ERR "invalid uac2 rates\n");

				break;

			}

sound/usb/quirks.c

+5 −1
Original line number Diff line number Diff line
@@ -136,6 +136,10 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, 
		snd_printk(KERN_ERR "cannot memdup\n");

		return -ENOMEM;

	}

	if (fp->nr_rates > MAX_NR_RATES) {

		kfree(fp);

		return -EINVAL;

	}

	if (fp->nr_rates > 0) {

		rate_table = kmemdup(fp->rate_table,

				     sizeof(int) * fp->nr_rates, GFP_KERNEL);