On Wed, 30 Mar 2016 21:03:22 +0200, Vladis Dronov wrote:
There is a double-free bug in [snd-usb-audio] module due to alloc/free logic flaw in snd_usb_add_audio_stream() function. This leads to kernel structures corruption and panic. Fix the code flow and alloc/free logic so there is no double-free.
The detailed analysis: https://bugzilla.redhat.com/show_bug.cgi?id=1283358
Reported-by: Ralf Spenneberg ralf@spenneberg.net Signed-off-by: Vladis Dronov vdronov@redhat.com
Thanks for the report. But how about a simpler fix like below?
Takashi
--- diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c index fb62bce2435c..0e154ae7924e 100644 --- a/sound/usb/quirks.c +++ b/sound/usb/quirks.c @@ -150,6 +150,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, 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; @@ -193,8 +194,11 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, return 0;
error: - kfree(fp); - kfree(rate_table); + /* linked fp will be removed in snd_usb_audio_pcm_free() */ + if (list_empty(&fp->list)) { + kfree(fp); + kfree(rate_table); + } return err; }