This is a note to let you know that I've just added the patch titled ALSA: usb-audio: Fix double-free in error paths after snd_usb_add_audio_stream() call to the 3.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: alsa-usb-audio-fix-double-free-in-error-paths-after-snd_usb_add_audio_stream-call.patch and it can be found in the queue-3.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 836b34a935abc91e13e63053d0a83b24dfb5ea78 Mon Sep 17 00:00:00 2001 From: Vladis Dronov <vdronov@xxxxxxxxxx> 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 From: Vladis Dronov <vdronov@xxxxxxxxxx> 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 <tiwai@xxxxxxx> [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 <ralf@xxxxxxxxxxxxxx> Signed-off-by: Vladis Dronov <vdronov@xxxxxxxxxx> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 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; @@ -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, @@ -662,6 +664,7 @@ 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 */ @@ -710,6 +713,7 @@ int snd_usb_parse_audio_interface(struct 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); Patches currently in stable-queue which might be from vdronov@xxxxxxxxxx are queue-3.14/alsa-usb-audio-fix-double-free-in-error-paths-after-snd_usb_add_audio_stream-call.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html