From 370aadd16d1397a4d089d26a53a02a8117f699e7 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Tue, 14 Jan 2020 09:39:53 +0100 Subject: [PATCH] ALSA: usb-audio: fix sync-ep altsetting sanity check commit 5d1b71226dc4d44b4b65766fa9d74492f9d4587b upstream. 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 # 3.5 Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20200114083953.1106-1-johan@kernel.org Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- 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 a04c727dcd19..fa24bd491cf6 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];