From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5CB3037CD59; Thu, 30 Jul 2026 15:43:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785426219; cv=none; b=pEqYaWfCEUB38Vqr6MuMGYkeZCkJTpRBBV39RvcwqzPdENfjpanIgQ0LLOLDKA1J5xa1jpMUxkE5shbBqF6BlgSct35T2Wtvn+94793AhuAhiP0DqBNT1B7oKOxAwRWc6SMZdkPoEMZVWYpaHbjuw8zhMLLFKK0v5iRRuSS0sIw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785426219; c=relaxed/simple; bh=6Qi3oXESWEYndv5kZnTpPIJWuTJ9slIMUFh1zSEb6Zk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pA1gTuRUrmNhjAz8s8llmwq32hJ/FceTV8pThbrFocVAAEOGEiQaKMnHmQboYESSDtcsyWQo+4J4EP+XZAsav0L5FWOScsDst/1i6aTp/KxMNEc9OTt2bqBRQzAy9rp9tXYGQAcUmerUA2n5ltq07W3BfyJ9JdCRDHOyCa8d+HA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h8r//wmn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="h8r//wmn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD4551F000E9; Thu, 30 Jul 2026 15:43:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785426218; bh=cpgpukrGrlPqlSHO+e4Ik4UI3z2bcfNExKigcVewIDg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=h8r//wmnmdaZODkMCC8okOCgRncndLLh0TUdEUFskPVSPxb/fcw4Wd9UiWjC5d6jU Zjepp2CDj8PPuNHUyMTu0zofwM1tanuAAhVB7esDv8xHZ+VwXZpmzaW8Ao/vUhemap HEsH7yVHhg5ZjzZVqq8f/f/4/qXixNcebtR4tuXM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Norbert Szetei , Takashi Iwai Subject: [PATCH 6.12 343/602] ALSA: seq: close a re-opened queue timer in the destructor Date: Thu, 30 Jul 2026 16:12:15 +0200 Message-ID: <20260730141443.168601860@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141435.976815864@linuxfoundation.org> References: <20260730141435.976815864@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Norbert Szetei commit 2c4dc0ed50b05cd847a4b34b8cebf0775f19aeb9 upstream. queue_delete() closes the queue timer, then frees it. snd_seq_timer_close() clears q->timer->timeri. snd_use_lock_sync() then drains borrowers, and snd_seq_timer_delete() frees q->timer. A borrower can re-open the timer inside that window. A SET_QUEUE_CLIENT that took a queueptr() use_lock reference before the queue was unlinked runs snd_seq_timer_open() after the close. Open refuses re-open only while timeri is set, and the close just cleared it, so it re-opens timeri. snd_seq_timer_delete() does not close that instance. Its snd_seq_timer_stop() is a no-op, because running was cleared first. So it frees q->timer with the instance still live. The queue is freed next. The instance stays on the global timer with callback_data pointing at the freed queue. A non-owner START on the unlocked queue arms it. The next tick derefs the freed queue in snd_seq_timer_interrupt(). Reachable by an unprivileged user with access to /dev/snd/seq. No CAP and no queue ownership required. Close any lingering instance in the destructor. There, ->timeri can no longer change: the queue is unlinked and all use_lock borrowers have drained, so no snd_seq_queue_use() can re-open it. Close it before clearing q->timer. snd_timer_close() waits for any in-flight snd_seq_timer_interrupt() to finish, and that callback still reads q->timer (via snd_seq_check_queue()), so q->timer must stay valid until it drains. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Norbert Szetei Link: https://patch.msgid.link/422FDB81-2A68-47C7-A22D-2D3301E2E86D@doyensec.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/seq/seq_timer.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) --- a/sound/core/seq/seq_timer.c +++ b/sound/core/seq/seq_timer.c @@ -61,12 +61,23 @@ struct snd_seq_timer *snd_seq_timer_new( void snd_seq_timer_delete(struct snd_seq_timer **tmr) { struct snd_seq_timer *t = *tmr; - *tmr = NULL; + struct snd_timer_instance *ti; if (t == NULL) { pr_debug("ALSA: seq: snd_seq_timer_delete() called with NULL timer\n"); return; } + + scoped_guard(spinlock_irq, &t->lock) { + ti = t->timeri; + t->timeri = NULL; + } + if (ti) { + snd_timer_close(ti); + snd_timer_instance_free(ti); + } + + *tmr = NULL; t->running = 0; /* reset time */