linux-kernel - Re: kmemleak findings about USB audio recording on 3.3.2

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Date:	Fri, 18 May 2012 18:00:43 +0200
From:	Clemens Ladisch <clemens@...isch.de>
To:	"Alexander E. Patrakov" <patrakov@...il.com>
CC:	linux-kernel@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: kmemleak findings about USB audio recording on 3.3.2

Alexander E. Patrakov wrote:
> On my home computer with linux-3.3.2, kmemleak found a lot of copies of
> this (not only from pulseaudio, but also from wine):
>
> unreferenced object 0xffff88021afaed40 (size 16):
>   comm "pulseaudio", pid 839, jiffies 4294711382 (age 31392.844s)
>   hex dump (first 16 bytes):
>     80 3e 00 00 c0 5d 00 00 00 7d 00 00 02 00 00 00  .>...]...}......
>   backtrace:
>     [<ffffffff811620d7>] create_object+0x127/0x2b0
>     [<ffffffff81636d81>] kmemleak_alloc+0x21/0x50
>     [<ffffffff81157bc3>] __kmalloc+0x103/0x1e0
>     [<ffffffffa02f650b>] snd_usb_pcm_open+0x3bb/0x4c0 [snd_usb_audio]

Please try this patch.

--8<---------------------------------------------------------------->8--
ALSA: usb-audio: fix rate_list memory leak

The array of sample rates is reallocated every time when opening
the PCM device, but was freed only once when unplugging the device.

Reported-by: "Alexander E. Patrakov" <patrakov@...il.com>
Signed-off-by: Clemens Ladisch <clemens@...isch.de>
---
 sound/usb/pcm.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -783,6 +783,9 @@ static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
 	int count = 0, needs_knot = 0;
 	int err;

+	kfree(subs->rate_list.list);
+	subs->rate_list.list = NULL;
+
 	list_for_each_entry(fp, &subs->fmt_list, list) {
 		if (fp->rates & SNDRV_PCM_RATE_CONTINUOUS)
 			return 0;
--
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