All of lore.kernel.org
 help / color / mirror / Atom feed
From: Xiyu Yang <xiyuyang19@fudan.edu.cn>
To: Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
	Xin Tan <tanxin.ctf@gmail.com>, "Geoffrey D. Bennett" <g@b4.vu>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Colin Ian King <colin.king@canonical.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	Xiyu Yang <xiyuyang19@fudan.edu.cn>,
	alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org
Cc: yuanxzhang@fudan.edu.cn, kjlu@umn.edu
Subject: [PATCH] ALSA: usb-audio: Fix usb audio refcnt leak when getting spdif
Date: Thu, 23 Apr 2020 12:54:19 +0800	[thread overview]
Message-ID: <1587617711-13200-1-git-send-email-xiyuyang19@fudan.edu.cn> (raw)

snd_microii_spdif_default_get() invokes snd_usb_lock_shutdown(), which
increases the refcount of the snd_usb_audio object "chip".

When snd_microii_spdif_default_get() returns, local variable "chip"
becomes invalid, so the refcount should be decreased to keep refcount
balanced.

The reference counting issue happens in several exception handling paths
of snd_microii_spdif_default_get(). When those error scenarios occur
such as usb_ifnum_to_if() returns NULL, the function forgets to decrease
the refcnt increased by snd_usb_lock_shutdown(), causing a refcnt leak.

Fix this issue by jumping to "end" label when those error scenarios
occur.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
---
 sound/usb/mixer_quirks.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index c237e24f08d9..0f072426b84c 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -1508,11 +1508,15 @@ static int snd_microii_spdif_default_get(struct snd_kcontrol *kcontrol,
 
 	/* use known values for that card: interface#1 altsetting#1 */
 	iface = usb_ifnum_to_if(chip->dev, 1);
-	if (!iface || iface->num_altsetting < 2)
-		return -EINVAL;
+	if (!iface || iface->num_altsetting < 2) {
+		err = -EINVAL;
+		goto end;
+	}
 	alts = &iface->altsetting[1];
-	if (get_iface_desc(alts)->bNumEndpoints < 1)
-		return -EINVAL;
+	if (get_iface_desc(alts)->bNumEndpoints < 1) {
+		err = -EINVAL;
+		goto end;
+	}
 	ep = get_endpoint(alts, 0)->bEndpointAddress;
 
 	err = snd_usb_ctl_msg(chip->dev,
-- 
2.7.4


             reply	other threads:[~2020-04-23  5:02 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-23  4:54 Xiyu Yang [this message]
2020-04-23  7:11 ` Takashi Iwai
2020-04-23  7:11   ` Takashi Iwai

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1587617711-13200-1-git-send-email-xiyuyang19@fudan.edu.cn \
    --to=xiyuyang19@fudan.edu.cn \
    --cc=alsa-devel@alsa-project.org \
    --cc=colin.king@canonical.com \
    --cc=g@b4.vu \
    --cc=gregkh@linuxfoundation.org \
    --cc=kjlu@umn.edu \
    --cc=linux-kernel@vger.kernel.org \
    --cc=perex@perex.cz \
    --cc=pierre-louis.bossart@linux.intel.com \
    --cc=tanxin.ctf@gmail.com \
    --cc=tglx@linutronix.de \
    --cc=tiwai@suse.com \
    --cc=yuanxzhang@fudan.edu.cn \
    --subject='Re: [PATCH] ALSA: usb-audio: Fix usb audio refcnt leak when getting spdif' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.