From: Johan Hovold johan@kernel.org
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 stable@vger.kernel.org # 3.5 Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20200114083953.1106-1-johan@kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sudip Mukherjee sudipm.mukherjee@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- sound/usb/pcm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -369,7 +369,7 @@ static int set_sync_ep_implicit_fb_quirk 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];