101 lines
3.8 KiB
Diff
101 lines
3.8 KiB
Diff
From 1b9e866417f77622b03f5b9c4e2845133054e670 Mon Sep 17 00:00:00 2001
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From: Vladis Dronov <vdronov@redhat.com>
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Date: Thu, 31 Mar 2016 12:05:43 -0400
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Subject: [PATCH 2/2] ALSA: usb-audio: Fix double-free in error paths after
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snd_usb_add_audio_stream() call
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create_fixed_stream_quirk(), snd_usb_parse_audio_interface() and
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create_uaxx_quirk() functions allocate the audioformat object by themselves
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and free it upon error before returning. However, once the object is linked
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to a stream, it's freed again in snd_usb_audio_pcm_free(), thus it'll be
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double-freed, eventually resulting in a memory corruption.
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This patch fixes these failures in the error paths by unlinking the audioformat
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object before freeing it.
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Based on a patch by Takashi Iwai" <tiwai@suse.de>
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[Note for stable backports:
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this patch requires the commit 902eb7fd1e4a ('ALSA: usb-audio: Minor
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code cleanup in create_fixed_stream_quirk()')]
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1283358
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Reported-by: Ralf Spenneberg <ralf@spenneberg.net>
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Cc: <stable@vger.kernel.org> # see the note above
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Signed-off-by: Vladis Dronov <vdronov@redhat.com>
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---
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sound/usb/quirks.c | 4 ++++
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sound/usb/stream.c | 6 +++++-
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2 files changed, 9 insertions(+), 1 deletion(-)
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diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
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index 2f0bbc43f902..6f68ba9bda8a 100644
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--- a/sound/usb/quirks.c
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+++ b/sound/usb/quirks.c
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@@ -150,6 +150,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip,
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usb_audio_err(chip, "cannot memdup\n");
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return -ENOMEM;
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}
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+ INIT_LIST_HEAD(&fp->list);
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if (fp->nr_rates > MAX_NR_RATES) {
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kfree(fp);
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return -EINVAL;
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@@ -193,6 +194,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip,
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return 0;
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error:
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+ list_del(&fp->list); /* unlink for avoiding double-free */
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kfree(fp);
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kfree(rate_table);
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return err;
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@@ -468,6 +470,7 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip,
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fp->ep_attr = get_endpoint(alts, 0)->bmAttributes;
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fp->datainterval = 0;
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fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
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+ INIT_LIST_HEAD(&fp->list);
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switch (fp->maxpacksize) {
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case 0x120:
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@@ -491,6 +494,7 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip,
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? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
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err = snd_usb_add_audio_stream(chip, stream, fp);
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if (err < 0) {
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+ list_del(&fp->list); /* unlink for avoiding double-free */
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kfree(fp);
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return err;
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}
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diff --git a/sound/usb/stream.c b/sound/usb/stream.c
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index 8ee14f2365e7..3b23102230c0 100644
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--- a/sound/usb/stream.c
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+++ b/sound/usb/stream.c
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@@ -316,7 +316,9 @@ static struct snd_pcm_chmap_elem *convert_chmap(int channels, unsigned int bits,
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/*
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* add this endpoint to the chip instance.
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* if a stream with the same endpoint already exists, append to it.
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- * if not, create a new pcm stream.
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+ * if not, create a new pcm stream. note, fp is added to the substream
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+ * fmt_list and will be freed on the chip instance release. do not free
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+ * fp or do remove it from the substream fmt_list to avoid double-free.
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*/
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int snd_usb_add_audio_stream(struct snd_usb_audio *chip,
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int stream,
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@@ -677,6 +679,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
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* (fp->maxpacksize & 0x7ff);
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fp->attributes = parse_uac_endpoint_attributes(chip, alts, protocol, iface_no);
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fp->clock = clock;
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+ INIT_LIST_HEAD(&fp->list);
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/* some quirks for attributes here */
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@@ -725,6 +728,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
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dev_dbg(&dev->dev, "%u:%d: add audio endpoint %#x\n", iface_no, altno, fp->endpoint);
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err = snd_usb_add_audio_stream(chip, stream, fp);
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if (err < 0) {
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+ list_del(&fp->list); /* unlink for avoiding double-free */
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kfree(fp->rate_table);
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kfree(fp->chmap);
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kfree(fp);
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--
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2.5.5
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