From aeea4acc3327edf231266bd8225e0af559dd5f79 Mon Sep 17 00:00:00 2001 From: Vladis Dronov Date: Thu, 31 Mar 2016 12:05:43 -0400 Subject: ALSA: usb-audio: Fix double-free in error paths after snd_usb_add_audio_stream() call 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()')] Bug 1823317 Bug 1935735 Change-Id: I4f65a902a19e7b21e8bc0fa21efd833c8360a3cf Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1283358 Reported-by: Ralf Spenneberg Cc: # see the note above Signed-off-by: Vladis Dronov Signed-off-by: Takashi Iwai Signed-off-by: Gagan Grover Reviewed-on: http://git-master/r/1259999 (cherry picked from commit 14e09c3233fb7578c778b70ec3933ba5cadfccb6) Reviewed-on: https://git-master.nvidia.com/r/1690292 GVS: Gerrit_Virtual_Submit Reviewed-by: Bibek Basu Tested-by: Amulya Yarlagadda Reviewed-by: Winnie Hsu --- sound/usb/quirks.c | 17 +++++++++++------ sound/usb/stream.c | 6 +++++- 2 files changed, 16 insertions(+), 7 deletions(-) (limited to 'sound') diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c index 3879eae7e874..a72bfeee6de2 100644 --- a/sound/usb/quirks.c +++ b/sound/usb/quirks.c @@ -136,6 +136,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, snd_printk(KERN_ERR "cannot memdup\n"); return -ENOMEM; } + INIT_LIST_HEAD(&fp->list); if (fp->nr_rates > MAX_NR_RATES) { kfree(fp); return -EINVAL; @@ -154,15 +155,12 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, ? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK; err = snd_usb_add_audio_stream(chip, stream, fp); if (err < 0) { - kfree(fp); - kfree(rate_table); - return err; + goto error; } if (fp->iface != get_iface_desc(&iface->altsetting[0])->bInterfaceNumber || fp->altset_idx >= iface->num_altsetting) { - kfree(fp); - kfree(rate_table); - return -EINVAL; + err = -EINVAL; + goto error; } alts = &iface->altsetting[fp->altset_idx]; if (fp->datainterval == 0) @@ -173,6 +171,11 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, snd_usb_init_pitch(chip, fp->iface, alts, fp); snd_usb_init_sample_rate(chip, fp->iface, alts, fp, fp->rate_max); return 0; +error: + list_del(&fp->list); /* unlink for avoiding double-free */ + kfree(fp); + kfree(rate_table); + return err; } /* @@ -239,6 +242,7 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip, 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: @@ -262,6 +266,7 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip, ? 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; } diff --git a/sound/usb/stream.c b/sound/usb/stream.c index 5b6f7a027c6a..7ddf4a437e4a 100644 --- a/sound/usb/stream.c +++ b/sound/usb/stream.c @@ -307,7 +307,9 @@ static struct snd_pcm_chmap_elem *convert_chmap(int channels, unsigned int bits, /* * 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, @@ -755,6 +757,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no) fp->attributes = parse_uac_endpoint_attributes(chip, alts, protocol, iface_no); fp->clock = clock; fp->chmap = convert_chmap(num_channels, chconfig, protocol); + INIT_LIST_HEAD(&fp->list); /* some quirks for attributes here */ @@ -799,6 +802,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no) snd_printdd(KERN_INFO "%d:%u:%d: add audio endpoint %#x\n", dev->devnum, 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); -- cgit v1.2.3