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 9F39035839C for ; Wed, 13 May 2026 16:46:30 +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=1778690790; cv=none; b=WfpJBwecaXRZFeW+cCOm2IjBBWeGTdCbWHA5QYIaxyMM1w7qkTT2WyzvuYWD7TovEAcDWYIPoe6SnqwD0aP+YVwW/xrdG5g7nf+RRwQVLcR1GAGm00HafEzPHgabDlBCahw1npfpq0GlUjh9wzv9hcNovuRjXfS0xSXchrrLK8s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778690790; c=relaxed/simple; bh=b+4KQs7gl/zu4ynZobTCTqo8SzqANKKuYG/asWKjLuU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=STTuLKcUHGOJJiDVIqMjjvo5nhUuYOGoCbVnN8Pdm9aWdz+Iw3wPgCbQqWaOuxoPlHa6OW97BajqR0mcCfvVkqxqlwwSoRqtcLbZwpgDRQAoErKMltiqV6BMWwLpveKtQSS6RxCtZMsfUhqZqgWpM/hxFq3WYMdvWXgF5AP9hZk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KSAEeGKo; 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="KSAEeGKo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ADD1AC19425; Wed, 13 May 2026 16:46:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778690790; bh=b+4KQs7gl/zu4ynZobTCTqo8SzqANKKuYG/asWKjLuU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KSAEeGKo4VpbTJ66HTlX5BL16VatUdzcn4hhKoZlImkkJn/eoprzT2JYSlmR2goHP 4wB5t5FYeQekvrR36vhvSQzSzcqfeIaHSf3FOgX7NREpAIE5kFAdX7b2TSi1aPm82I Nb+R6Ahrvr8bJepn0qKlRwU1b7D6hQsrG1FnlPpJQCoE3hNJ8pd4ygD1WRh4lq+LPB Tzdr9sXaMW53cyePDbLfbKCGDI3gRi5X7YSFLxHJHvC8kWnqnQq6pjp5527TYy0J3x 7unf5BtrvuO988JfkSybfiawgL0Gmhs9A9TpXqsRAiX9vg3dooLXdqJ8Q2PXF7bHHM 2tC/nFw8MxjSw== From: Sasha Levin To: stable@vger.kernel.org Cc: =?UTF-8?q?C=C3=A1ssio=20Gabriel?= , Takashi Iwai , Sasha Levin Subject: [PATCH 5.10.y] ALSA: core: Serialize deferred fasync state checks Date: Wed, 13 May 2026 12:46:26 -0400 Message-ID: <20260513164626.3816356-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026051257-shopping-sitcom-fcf1@gregkh> References: <2026051257-shopping-sitcom-fcf1@gregkh> 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 [ converted upstream guard()/scoped_guard() to explicit spin_lock_irqsave/spin_lock_irq and dropped the list_del_init() from a missing prerequisite ] Signed-off-by: Sasha Levin --- sound/core/misc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/sound/core/misc.c b/sound/core/misc.c index c3f3d94b51970..51f175b2f9c8e 100644 --- a/sound/core/misc.c +++ b/sound/core/misc.c @@ -219,9 +219,13 @@ void snd_kill_fasync(struct snd_fasync *fasync, int signal, int poll) { unsigned long flags; - if (!fasync || !fasync->on) + if (!fasync) return; spin_lock_irqsave(&snd_fasync_lock, flags); + if (!fasync->on) { + spin_unlock_irqrestore(&snd_fasync_lock, flags); + return; + } fasync->signal = signal; fasync->poll = poll; list_move(&fasync->list, &snd_fasync_list); @@ -234,7 +238,9 @@ void snd_fasync_free(struct snd_fasync *fasync) { if (!fasync) return; + spin_lock_irq(&snd_fasync_lock); fasync->on = 0; + spin_unlock_irq(&snd_fasync_lock); flush_work(&snd_fasync_work); kfree(fasync); } -- 2.53.0