From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9C56D30ACF0 for ; Wed, 13 May 2026 14:34:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778682877; cv=none; b=tuLGJ5sgMSAxIenTzbtczBekMO1K9stpwiDtD1iTu80YrZ6aJ9cQ5ss9RVL5kzW6dpwOTYommK62Tyx0Snh9Lxg/Xc70KlLA5p5n7Pbb0H/YjanfIQh2Rhi64viI3tHyy6GDqG1th8olq3oABtbMO3GlvIS1NkJyL4tJ4gbXl4Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778682877; c=relaxed/simple; bh=A9qL67fRAZqQZ5fN5HLDD9iRYpULquQ37/ahXEYuxts=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=pFD+LLBYJxt2Vbys7/pR6T+RIbZY/KnDZZlbLizNjYXQUOG7JYqCwLzPNQJ9GrOyJHPTT9GgrEoOdyx5uKaL9eWKrRqfXPgv82mFtxkOohjkNJjKuxMz/ceyRffOqwdbw5id1R4IWmH6qWc+zbEMnh6MqhM8ss1x1LFYDe7T8Tw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Pws5wOi0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Pws5wOi0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3D66C19425; Wed, 13 May 2026 14:34:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778682877; bh=A9qL67fRAZqQZ5fN5HLDD9iRYpULquQ37/ahXEYuxts=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Pws5wOi0bKq2HuoOkgqAE742lFKaE9wMDBWjXK+ymgBc7C5A8enJ4QBaxhhXd2LOk fOE74DugNspHCRiaiutZzZ/2rz3IOtzlbQB1dMf/Ee1/WSu2lfPVzCsrss7YzI3z1n MEmCI0Jwp+KtD3egW39+QWxjpxq8eWzu3UTZ2EAnBaZ3u2oVFChedS82QEzk9QsW7B 4KayD4KTa5reZojPhohMyIpEwwSnsfB0A1ma4OzvR/7nt2klF4G55ctNNfb1wpB/Hp xvB4Z4VS5VEqIvkvsHsUk8DJVCpO7HZWPUkz9NMuBrYznmnh7EnmfL01RLN3vkuGf6 UpEhfKGBlxvxw== From: Sasha Levin To: stable@vger.kernel.org Cc: =?UTF-8?q?C=C3=A1ssio=20Gabriel?= , Takashi Iwai , Sasha Levin Subject: [PATCH 6.1.y 3/3] ALSA: core: Serialize deferred fasync state checks Date: Wed, 13 May 2026 10:34:33 -0400 Message-ID: <20260513143433.3755085-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260513143433.3755085-1-sashal@kernel.org> References: <2026051252-doozy-thyself-9752@gregkh> <20260513143433.3755085-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Cássio Gabriel [ Upstream commit 5337213381df578058e2e41da93cbd0e4639935f ] snd_fasync_helper() updates fasync->on under snd_fasync_lock, and snd_fasync_work_fn() now also evaluates fasync->on under the same lock. snd_kill_fasync() still tests the flag before taking the lock, leaving an unsynchronized read against FASYNC enable/disable updates. Move the enabled-state check into the locked section. Also clear fasync->on under snd_fasync_lock in snd_fasync_free() before unlinking the pending entry. Together with the locked sender-side check, this publishes teardown before flushing the deferred work and prevents a racing sender from requeueing the entry after free has started. Fixes: ef34a0ae7a26 ("ALSA: core: Add async signal helpers") Fixes: 8146cd333d23 ("ALSA: core: Fix potential data race at fasync handling") Cc: stable@vger.kernel.org Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260506-alsa-core-fasync-on-lock-v1-1-ea48c77d6ca4@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/core/misc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/sound/core/misc.c b/sound/core/misc.c index 918d59a541c82..fd891a3ceb963 100644 --- a/sound/core/misc.c +++ b/sound/core/misc.c @@ -219,9 +219,11 @@ EXPORT_SYMBOL_GPL(snd_fasync_helper); void snd_kill_fasync(struct snd_fasync *fasync, int signal, int poll) { - if (!fasync || !fasync->on) + if (!fasync) return; guard(spinlock_irqsave)(&snd_fasync_lock); + if (!fasync->on) + return; fasync->signal = signal; fasync->poll = poll; list_move(&fasync->list, &snd_fasync_list); @@ -234,8 +236,10 @@ void snd_fasync_free(struct snd_fasync *fasync) if (!fasync) return; - scoped_guard(spinlock_irq, &snd_fasync_lock) + scoped_guard(spinlock_irq, &snd_fasync_lock) { + fasync->on = 0; list_del_init(&fasync->list); + } flush_work(&snd_fasync_work); kfree(fasync); -- 2.53.0