blob: d722a88c036ce8764a6024dd4fb8b6875b421af2 [file] [log] [blame]
From e9eade7a205e197eb546ce283c199f7f3594dd3a Mon Sep 17 00:00:00 2001
From: Johan Hovold <>
Date: Fri, 20 Dec 2019 10:31:34 +0100
Subject: [PATCH] ALSA: usb-audio: fix set_format altsetting sanity check
commit 0141254b0a74b37aa7eb13d42a56adba84d51c73 upstream.
Make sure to check the return value of usb_altnum_to_altsetting() to
avoid dereferencing a NULL pointer when the requested alternate settings
is missing.
The format altsetting number may come from a quirk table and there does
not seem to be any other validation of it (the corresponding index is
checked however).
Fixes: b099b9693d23 ("ALSA: usb-audio: Avoid superfluous usb_set_interface() calls")
Cc: stable <> # 4.18
Signed-off-by: Johan Hovold <>
Signed-off-by: Takashi Iwai <>
Signed-off-by: Paul Gortmaker <>
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index ff5ab24f3bd1..624bcef9fb63 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -506,9 +506,9 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
if (WARN_ON(!iface))
return -EINVAL;
alts = usb_altnum_to_altsetting(iface, fmt->altsetting);
- altsd = get_iface_desc(alts);
- if (WARN_ON(altsd->bAlternateSetting != fmt->altsetting))
+ if (WARN_ON(!alts))
return -EINVAL;
+ altsd = get_iface_desc(alts);
if (fmt == subs->cur_audiofmt)
return 0;