5.15-stable review patch. If anyone has any objections, please let me know.

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From: Haein Lee lhi0729@kaist.ac.kr

[ Upstream commit 632108ec072ad64c8c83db6e16a7efee29ebfb74 ]

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 lhi0729@kaist.ac.kr Link: https://patch.msgid.link/vwhzmoba9j2f.vwhzmob9u9e2.g6@dooray.com Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- sound/usb/mixer.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index 5163d5e7682e7..de80240d9ed58 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -3071,6 +3071,8 @@ 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++) {