Re: [PATCH] ALSA: usb-audio: Fix double-free in snd_usb_add_audio_stream()

From: Takashi Iwai
Date: Thu Mar 31 2016 - 12:13:32 EST

On Thu, 31 Mar 2016 18:05:43 +0200,
Vladis Dronov wrote:
> From: Vladis Dronov <vdronov@xxxxxxxxxx>
> Subject: [PATCH] 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" <tiwai@xxxxxxx>
> [Note for stable backports:
> this patch requires the commit 902eb7fd1e4a ('ALSA: usb-audio: Minor
> code cleanup in create_fixed_stream_quirk()')]
> Bugzilla:
> Reported-by: Ralf Spenneberg <ralf@xxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # see the note above
> Signed-off-by: Vladis Dronov <vdronov@xxxxxxxxxx>

Applied, thanks.