Commit 632108ec authored by Haein Lee's avatar Haein Lee Committed by Takashi Iwai
Browse files

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: 17156f23 ("ALSA: usb: add UAC3 BADD profiles support")
Signed-off-by: default avatarHaein Lee <lhi0729@kaist.ac.kr>
Link: https://patch.msgid.link/vwhzmoba9j2f.vwhzmob9u9e2.g6@dooray.com


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 05a1fc5e

sound/usb/mixer.c

+2 −0
Original line number Diff line number Diff line
@@ -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++) {