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Thu, 27 Aug 2026 11:39:53 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id roQWFAkikGpTfQAAD6G6ig (envelope-from ); Thu, 27 Aug 2026 11:39:53 +0000 From: Takashi Iwai To: linux-sound@vger.kernel.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH] ALSA: control: Don't add invalid kcontrols to LED layer Date: Thu, 27 Aug 2026 13:39:03 +0200 Message-ID: <20260827113951.893291-1-tiwai@suse.de> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Level: X-Spam-Score: -2.80 X-Spam-Flag: NO X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-0.993]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_TWO(0.00)[2]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:email,suse.de:mid]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; FROM_EQ_ENVFROM(0.00)[]; TO_DN_NONE(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[] The kcontrol LED state layer tries to track the all associated kcontrol elements with naive assumptions that they are readable. But one can create a write-only element that has no get callback (even a user element can do it), and this may lead to a NULL dereference at the call chain of snd_ctl_led_notify(), as found by syzkaller. For avoiding the Oops, add a sanity check of the kcontrol's info and get callbacks, and just skip the invalid kcontrols before assigning the kctl to the LED layer. Reported-by: syzbot+b7fe2760ea6f1ee44b4d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/6a9007b3.1d9ded08.62e62.00cd.GAE@google.com Fixes: 22d8de62f11b ("ALSA: control - add generic LED trigger module as the new control layer") Signed-off-by: Takashi Iwai --- sound/core/control_led.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sound/core/control_led.c b/sound/core/control_led.c index 8cbacee57ce7..3d13bbec1c54 100644 --- a/sound/core/control_led.c +++ b/sound/core/control_led.c @@ -255,6 +255,8 @@ static int snd_ctl_led_set_id(int card_number, struct snd_ctl_elem_id *id, kctl = snd_ctl_find_id(card, id); if (!kctl) return -ENOENT; + if (!kctl->info || !kctl->get) + return -EINVAL; ioff = snd_ctl_get_ioff(kctl, id); vd = &kctl->vd[ioff]; access = vd->access & SNDRV_CTL_ELEM_ACCESS_LED_MASK; -- 2.55.0