Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754704AbcD0AG6 (ORCPT ); Tue, 26 Apr 2016 20:06:58 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:40121 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754037AbcDZXOD (ORCPT ); Tue, 26 Apr 2016 19:14:03 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Vladis Dronov" , "Takashi Iwai" , "Ralf Spenneberg" Date: Wed, 27 Apr 2016 01:02:21 +0200 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 154/217] ALSA: usb-audio: Fix double-free in error paths after snd_usb_add_audio_stream() call In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8426:ae4:c500:9cba:69ae:962d:6167 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3453 Lines: 96 3.16.35-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Vladis Dronov commit 836b34a935abc91e13e63053d0a83b24dfb5ea78 upstream. create_fixed_stream_quirk(), snd_usb_parse_audio_interface() and create_uaxx_quirk() functions allocate the audioformat object by themselves and free it upon error before returning. However, once the object is linked to a stream, it's freed again in snd_usb_audio_pcm_free(), thus it'll be double-freed, eventually resulting in a memory corruption. This patch fixes these failures in the error paths by unlinking the audioformat object before freeing it. Based on a patch by Takashi Iwai [Note for stable backports: this patch requires the commit 902eb7fd1e4a ('ALSA: usb-audio: Minor code cleanup in create_fixed_stream_quirk()')] Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1283358 Reported-by: Ralf Spenneberg Signed-off-by: Vladis Dronov Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- sound/usb/quirks.c | 4 ++++ sound/usb/stream.c | 6 +++++- 2 files changed, 9 insertions(+), 1 deletion(-) --- a/sound/usb/quirks.c +++ b/sound/usb/quirks.c @@ -138,6 +138,7 @@ static int create_fixed_stream_quirk(str usb_audio_err(chip, "cannot memdup\n"); return -ENOMEM; } + INIT_LIST_HEAD(&fp->list); if (fp->nr_rates > MAX_NR_RATES) { kfree(fp); return -EINVAL; @@ -181,6 +182,7 @@ static int create_fixed_stream_quirk(str return 0; error: + list_del(&fp->list); /* unlink for avoiding double-free */ kfree(fp); kfree(rate_table); return err; @@ -456,6 +458,7 @@ static int create_uaxx_quirk(struct snd_ fp->ep_attr = get_endpoint(alts, 0)->bmAttributes; fp->datainterval = 0; fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize); + INIT_LIST_HEAD(&fp->list); switch (fp->maxpacksize) { case 0x120: @@ -479,6 +482,7 @@ static int create_uaxx_quirk(struct snd_ ? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK; err = snd_usb_add_audio_stream(chip, stream, fp); if (err < 0) { + list_del(&fp->list); /* unlink for avoiding double-free */ kfree(fp); return err; } --- a/sound/usb/stream.c +++ b/sound/usb/stream.c @@ -315,7 +315,9 @@ static struct snd_pcm_chmap_elem *conver /* * add this endpoint to the chip instance. * if a stream with the same endpoint already exists, append to it. - * if not, create a new pcm stream. + * if not, create a new pcm stream. note, fp is added to the substream + * fmt_list and will be freed on the chip instance release. do not free + * fp or do remove it from the substream fmt_list to avoid double-free. */ int snd_usb_add_audio_stream(struct snd_usb_audio *chip, int stream, @@ -668,6 +670,7 @@ int snd_usb_parse_audio_interface(struct * (fp->maxpacksize & 0x7ff); fp->attributes = parse_uac_endpoint_attributes(chip, alts, protocol, iface_no); fp->clock = clock; + INIT_LIST_HEAD(&fp->list); /* some quirks for attributes here */ @@ -716,6 +719,7 @@ int snd_usb_parse_audio_interface(struct dev_dbg(&dev->dev, "%u:%d: add audio endpoint %#x\n", iface_no, altno, fp->endpoint); err = snd_usb_add_audio_stream(chip, stream, fp); if (err < 0) { + list_del(&fp->list); /* unlink for avoiding double-free */ kfree(fp->rate_table); kfree(fp->chmap); kfree(fp);