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 A481C3EDE45; Tue, 12 May 2026 17:52:48 +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=1778608368; cv=none; b=ro6dsoFF4LHgMBIJYIZjnRvpgA3p7+WW/3I7hmcjydzS+PPXqxCbIoHgYKjGbgVH571AY/+/B2BSAiMhg+uN8+pAu7ElRIFjpEuY7amNIt9ZFxqzcDATwfVL9art9PkQnhygh/WWGVPNS8EdH1qxk/UyUPykQiyUlsBlQMAhbtE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778608368; c=relaxed/simple; bh=7Kdueo1Eef/cuYSjNVI/EAMvbxHddbKUWG0Ouk0B9z8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=BPCRLA66JCinHaETYF/1LwEtTddcntQ9ObO9KGX6N6nkRCp1RiBqH6kwMTIdAgfriio2QEXCEvsAY0xXLOMhffFXh4eUotLHa/FtYsk4wgnuzyRNuvUKGamyF/llMm3l5r3/TCgXZkq/ZG0hADYkvIyFoMLiEAWHRYP1XzekHR0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=l91U73S0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="l91U73S0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 154AFC2BCC7; Tue, 12 May 2026 17:52:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778608368; bh=7Kdueo1Eef/cuYSjNVI/EAMvbxHddbKUWG0Ouk0B9z8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l91U73S0XUyfIyp1jsXDGrQO4odFaRDz6M0XWk2dYTAlgM4ZT6lDioNGeTr/B7Zdb bzN05+HXzRJxwkMeQbZdX8FasV80U3h9yYWjCCpNw+t5gR12YLSZVWRZ8YhmumX4lG ySzQhjiDLTdT47c2PRi85/a1BckC9fDVG7JpdtNc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?C=C3=A1ssio=20Gabriel?= , Takashi Iwai Subject: [PATCH 6.18 052/270] ALSA: core: Serialize deferred fasync state checks Date: Tue, 12 May 2026 19:37:33 +0200 Message-ID: <20260512173939.547285385@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260512173938.452574370@linuxfoundation.org> References: <20260512173938.452574370@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cássio Gabriel commit 5337213381df578058e2e41da93cbd0e4639935f upstream. 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: Greg Kroah-Hartman --- sound/core/misc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/sound/core/misc.c +++ b/sound/core/misc.c @@ -148,9 +148,11 @@ 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); @@ -163,8 +165,10 @@ void snd_fasync_free(struct snd_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);