From ffb2759df7efbc00187bfd9d1072434a13a54139 Mon Sep 17 00:00:00 2001 From: Zheyu Ma Date: Fri, 15 Jul 2022 09:05:15 +0800 Subject: [PATCH] ALSA: bcd2000: Fix a UAF bug on the error path of probing When the driver fails in snd_card_register() at probe time, it will free the 'bcd2k->midi_out_urb' before killing it, which may cause a UAF bug. The following log can reveal it: [ 50.727020] BUG: KASAN: use-after-free in bcd2000_input_complete+0x1f1/0x2e0 [snd_bcd2000] [ 50.727623] Read of size 8 at addr ffff88810fab0e88 by task swapper/4/0 [ 50.729530] Call Trace: [ 50.732899] bcd2000_input_complete+0x1f1/0x2e0 [snd_bcd2000] Fix this by adding usb_kill_urb() before usb_free_urb(). Fixes: b47a22290d58 ("ALSA: MIDI driver for Behringer BCD2000 USB device") Signed-off-by: Zheyu Ma Cc: Link: https://lore.kernel.org/r/20220715010515.2087925-1-zheyuma97@gmail.com Signed-off-by: Takashi Iwai --- sound/usb/bcd2000/bcd2000.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/sound/usb/bcd2000/bcd2000.c b/sound/usb/bcd2000/bcd2000.c index cd4a0bc..7aec0a9 100644 --- a/sound/usb/bcd2000/bcd2000.c +++ b/sound/usb/bcd2000/bcd2000.c @@ -348,7 +348,8 @@ static int bcd2000_init_midi(struct bcd2000 *bcd2k) static void bcd2000_free_usb_related_resources(struct bcd2000 *bcd2k, struct usb_interface *interface) { - /* usb_kill_urb not necessary, urb is aborted automatically */ + usb_kill_urb(bcd2k->midi_out_urb); + usb_kill_urb(bcd2k->midi_in_urb); usb_free_urb(bcd2k->midi_out_urb); usb_free_urb(bcd2k->midi_in_urb); -- 2.7.4