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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: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Xi Wang 2012-02-14 05:18:48 -05:00 committed by Takashi Iwai
parent 27c3afe6e1
commit 8866f405ef
3 changed files with 7 additions and 4 deletions
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1
sound/usb/card.h
View File

@ -1,6 +1,7 @@
#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

4
sound/usb/format.c
View File

@ -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;
}

6
sound/usb/quirks.c
View File

@ -132,10 +132,14 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip,
unsigned *rate_table = NULL;
fp = kmemdup(quirk->data, sizeof(*fp), GFP_KERNEL);
if (! fp) {
if (!fp) {
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);