From: Haein Lee Date: Tue, 11 Nov 2025 15:37:54 +0000 (+0900) Subject: ALSA: usb-audio: Fix NULL pointer dereference in snd_usb_mixer_controls_badd X-Git-Tag: v6.18-rc6~20^2~3 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=632108ec072ad64c8c83db6e16a7efee29ebfb74;p=thirdparty%2Flinux.git ALSA: usb-audio: Fix NULL pointer dereference in snd_usb_mixer_controls_badd In snd_usb_create_streams(), for UAC version 3 devices, the Interface Association Descriptor (IAD) is retrieved via usb_ifnum_to_if(). If this call fails, a fallback routine attempts to obtain the IAD from the next interface and sets a BADD profile. However, snd_usb_mixer_controls_badd() assumes that the IAD retrieved from usb_ifnum_to_if() is always valid, without performing a NULL check. This can lead to a NULL pointer dereference when usb_ifnum_to_if() fails to find the interface descriptor. This patch adds a NULL pointer check after calling usb_ifnum_to_if() in snd_usb_mixer_controls_badd() to prevent the dereference. This issue was discovered by syzkaller, which triggered the bug by sending a crafted USB device descriptor. Fixes: 17156f23e93c ("ALSA: usb: add UAC3 BADD profiles support") Signed-off-by: Haein Lee Link: https://patch.msgid.link/vwhzmoba9j2f.vwhzmob9u9e2.g6@dooray.com Signed-off-by: Takashi Iwai --- diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index 6f00e0d52382..72b900505d2c 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -3086,6 +3086,8 @@ static int snd_usb_mixer_controls_badd(struct usb_mixer_interface *mixer, int i; assoc = usb_ifnum_to_if(dev, ctrlif)->intf_assoc; + if (!assoc) + return -EINVAL; /* Detect BADD capture/playback channels from AS EP descriptors */ for (i = 0; i < assoc->bInterfaceCount; i++) {