From 4c72b649cb557ff8b613b94bd68471ecfb42f0fb 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 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()')] Change-Id: Ia332409f06bbd20c0abf9cf915f4a041200e4736 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/endpoint.c | 2 ++ sound/usb/quirks.c | 4 ++++ 2 files changed, 6 insertions(+) diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index 05842c8..2d7b5e7 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -393,6 +393,7 @@ int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no) * (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 */ @@ -434,6 +435,7 @@ int snd_usb_parse_audio_endpoints(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_endpoint(chip, stream, fp); if (err < 0) { + list_del(&fp->list); /* unlink for avoiding double-free */ kfree(fp->rate_table); kfree(fp); return err; diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c index 39e5c77..d7f1822 100644 --- a/sound/usb/quirks.c +++ b/sound/usb/quirks.c @@ -139,6 +139,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, kfree(fp); return -EINVAL; } + INIT_LIST_HEAD(&fp->list); if (fp->nr_rates > 0) { rate_table = kmalloc(sizeof(int) * fp->nr_rates, GFP_KERNEL); if (!rate_table) { @@ -173,6 +174,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, return 0; error: + list_del(&fp->list); /* unlink for avoiding double-free */ kfree(fp); kfree(rate_table); return err; @@ -243,6 +245,7 @@ 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: @@ -266,6 +269,7 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip, ? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK; err = snd_usb_add_audio_endpoint(chip, stream, fp); if (err < 0) { + list_del(&fp->list); /* unlink for avoiding double-free */ kfree(fp); return err; } -- cgit v1.1