CVE-2026-90207

Status: UPDATED  |  Advisory ID: CVE-2026-90207

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

ALSA: seq: midi: Serialize input teardown with event_input

snd_midi_input_event() must not be running while a rawmidi substream is

closing, since this can lead to the trigger state becoming out-of-step

through this sequence in snd_rawmidi_input_trigger():

snd_rawmidi_input_trigger(up=0)

snd_midi_input_event()

-> snd_rawmidi_kernel_read()

-> snd_rawmidi_input_trigger(up=1)

-> cancel_work_sync()

which ends with the underlying device being active unexpectedly.

When this is called from close_substream(), further input can re-trigger

the input event leaving it running after rawmidi_release_priv() has set

rfile->rmidi to NULL which leads to:

Unable to handle kernel NULL pointer dereference at virtual address 00000000000000b0

Call trace:

snd_midi_input_event+0x3c/0x134 [snd_seq_midi] (P)

snd_rawmidi_input_event_work+0x1c/0x2c

process_one_work+0x150/0x3a4

worker_thread+0x190/0x318

Apply a similar approach to commit ef7607ab1c8ad ("ALSA: seq: midi:

Serialize output teardown with event_input") which fixed the same issue

in the output direction, but updated to use RCU following Takashi Iwai's

proposed follow-on patch [1].

With this change in place, midisynth_unsubscribe() clears the input file

so snd_midi_input_event() will not re-trigger the stream and will be

quiesced by the cancel_work_sync() in snd_rawmidi_input_trigger().

[1] https://lore.kernel.org/linux-sound/[email protected]/ (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References