6.6-stable review patch. If anyone has any objections, please let me know.
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From: Jeongjun Park aha310510@gmail.com
commit 9f2c0ac1423d5f267e7f1d1940780fc764b0fee3 upstream.
The previous commit 0718a78f6a9f ("ALSA: usb-audio: Kill timer properly at removal") patched a UAF issue caused by the error timer.
However, because the error timer kill added in this patch occurs after the endpoint delete, a race condition to UAF still occurs, albeit rarely.
Additionally, since kill-cleanup for urb is also missing, freed memory can be accessed in interrupt context related to urb, which can cause UAF.
Therefore, to prevent this, error timer and urb must be killed before freeing the heap memory.
Cc: stable@vger.kernel.org Reported-by: syzbot+f02665daa2abeef4a947@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f02665daa2abeef4a947 Fixes: 0718a78f6a9f ("ALSA: usb-audio: Kill timer properly at removal") Signed-off-by: Jeongjun Park aha310510@gmail.com Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- sound/usb/midi.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
--- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -1522,15 +1522,14 @@ static void snd_usbmidi_free(struct snd_ { int i;
+ if (!umidi->disconnected) + snd_usbmidi_disconnect(&umidi->list); + for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i) { struct snd_usb_midi_endpoint *ep = &umidi->endpoints[i]; - if (ep->out) - snd_usbmidi_out_endpoint_delete(ep->out); - if (ep->in) - snd_usbmidi_in_endpoint_delete(ep->in); + kfree(ep->out); } mutex_destroy(&umidi->mutex); - timer_shutdown_sync(&umidi->error_timer); kfree(umidi); }