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* [alsa-devel] [PATCH] ALSA: usb-audio: fix sync-ep altsetting sanity check
@ 2020-01-14  8:39 Johan Hovold
  2020-01-14  8:42 ` Takashi Iwai
  0 siblings, 1 reply; 2+ messages in thread
From: Johan Hovold @ 2020-01-14  8:39 UTC (permalink / raw)
  To: Takashi Iwai; +Cc: alsa-devel, Johan Hovold, linux-kernel, stable

The altsetting sanity check in set_sync_ep_implicit_fb_quirk() was
checking for there to be at least one altsetting but then went on to
access the second one, which may not exist.

This could lead to random slab data being used to initialise the sync
endpoint in snd_usb_add_endpoint().

Fixes: c75a8a7ae565 ("ALSA: snd-usb: add support for implicit feedback")
Fixes: ca10a7ebdff1 ("ALSA: usb-audio: FT C400 sync playback EP to capture EP")
Fixes: 5e35dc0338d8 ("ALSA: usb-audio: add implicit fb quirk for Behringer UFX1204")
Fixes: 17f08b0d9aaf ("ALSA: usb-audio: add implicit fb quirk for Axe-Fx II")
Fixes: 103e9625647a ("ALSA: usb-audio: simplify set_sync_ep_implicit_fb_quirk")
Cc: stable <stable@vger.kernel.org>     # 3.5
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 sound/usb/pcm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index a11c8150af58..0e4eab96e23e 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -370,7 +370,7 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 add_sync_ep_from_ifnum:
 	iface = usb_ifnum_to_if(dev, ifnum);
 
-	if (!iface || iface->num_altsetting == 0)
+	if (!iface || iface->num_altsetting < 2)
 		return -EINVAL;
 
 	alts = &iface->altsetting[1];
-- 
2.24.1

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^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [alsa-devel] [PATCH] ALSA: usb-audio: fix sync-ep altsetting sanity check
  2020-01-14  8:39 [alsa-devel] [PATCH] ALSA: usb-audio: fix sync-ep altsetting sanity check Johan Hovold
@ 2020-01-14  8:42 ` Takashi Iwai
  0 siblings, 0 replies; 2+ messages in thread
From: Takashi Iwai @ 2020-01-14  8:42 UTC (permalink / raw)
  To: Johan Hovold; +Cc: alsa-devel, linux-kernel, stable

On Tue, 14 Jan 2020 09:39:53 +0100,
Johan Hovold wrote:
> 
> The altsetting sanity check in set_sync_ep_implicit_fb_quirk() was
> checking for there to be at least one altsetting but then went on to
> access the second one, which may not exist.
> 
> This could lead to random slab data being used to initialise the sync
> endpoint in snd_usb_add_endpoint().
> 
> Fixes: c75a8a7ae565 ("ALSA: snd-usb: add support for implicit feedback")
> Fixes: ca10a7ebdff1 ("ALSA: usb-audio: FT C400 sync playback EP to capture EP")
> Fixes: 5e35dc0338d8 ("ALSA: usb-audio: add implicit fb quirk for Behringer UFX1204")
> Fixes: 17f08b0d9aaf ("ALSA: usb-audio: add implicit fb quirk for Axe-Fx II")
> Fixes: 103e9625647a ("ALSA: usb-audio: simplify set_sync_ep_implicit_fb_quirk")
> Cc: stable <stable@vger.kernel.org>     # 3.5
> Signed-off-by: Johan Hovold <johan@kernel.org>

Thanks, applied now.


Takashi
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2020-01-14  8:39 [alsa-devel] [PATCH] ALSA: usb-audio: fix sync-ep altsetting sanity check Johan Hovold
2020-01-14  8:42 ` Takashi Iwai

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