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 CCD2E2F6910 for ; Fri, 1 May 2026 11:56:30 +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=1777636590; cv=none; b=UeQeUOuYahH7REpb9HaPETo4hp5XlSkAYYP8/9yp+rDjXAQ8nD+pebKF5d6jgaCJJbmECsFYsyPybtFO6/TTV58pAfpPQo4q03V+Jo6NkKBjO5rQ1wQ6M7MV1d9L1mAY2gn+tVZxgls5jQmhWF8pbBLg1lEyH+hACovhJNaxjCU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777636590; c=relaxed/simple; bh=a7/PzT1cAd1zYoTCTnUQ4EicROuzI/23uAfWJjxWOb0=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=PGnMPeGd1njPdvZFc+204l3HmmoK6ZulbUkuu9JM7S6BTkypI3LK5aIOG+wFB/VdLNZUjdeYy+zFSTQ4t66dYD/ONWwf9OZCeNzPKVfxYMJznntrq6r1Szyy360p4Ow7OgmkJppBTw1sJbmyh/QJpDgQXMmwHmFDZSRFFROINVM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ERj5zRuP; 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="ERj5zRuP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66255C2BCB4; Fri, 1 May 2026 11:56:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777636590; bh=a7/PzT1cAd1zYoTCTnUQ4EicROuzI/23uAfWJjxWOb0=; h=Subject:To:Cc:From:Date:From; b=ERj5zRuPoDqEV0T8tg02j5XuhVdy4LEVEsPYYMHnZ5hb6FG0NVLUIoq3lE8FCD5/s 2logQaPizMBG1sjfO/YAF28fRJ0EfBHnnrJ3CcjSwpqjU69CK0b9uXBTiBeImCxROj /t5Ktrh0/PivjTqEv2liJNpmusVS0DyH/mo/iIoc= Subject: FAILED: patch "[PATCH] ALSA: core: Fix potential data race at fasync handling" failed to apply to 5.15-stable tree To: tiwai@suse.de,lamberson.jake@gmail.com,stable@vger.kernel.org Cc: From: Date: Fri, 01 May 2026 13:56:19 +0200 Message-ID: <2026050119-morale-scanning-6fc9@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=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 8146cd333d235ed32d48bb803fdf743472d7c783 # git commit -s git send-email --to '' --in-reply-to '2026050119-morale-scanning-6fc9@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 8146cd333d235ed32d48bb803fdf743472d7c783 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 20 Apr 2026 08:17:20 +0200 Subject: [PATCH] ALSA: core: Fix potential data race at fasync handling In snd_fasync_work_fn(), which is the offload work for traversing and processing the pending fasync list, the call of kill_fasync() is done outside the snd_fasync_lock for avoiding deadlocks. The problem is that its the references of fasync->on, fasync->signal and fasync->poll are done there also outside the lock. Since these may be modified by snd_kill_fasync() call concurrently from other process, inconsistent values might be passed to kill_fasync(). Although there shouldn't be critical UAF, it's still better to be addressed. This patch moves the kill_fasync() argument evaluations inside the snd_fasync_lock for avoiding the data races above. The handling in fasync->on flag is optimized in the loop to skip directly. Also, for more clarity, snd_fasync_free() takes the lock and unlink the pending entry more directly instead of clearing fasync->on flag. Reported-by: Jake Lamberson Fixes: ef34a0ae7a26 ("ALSA: core: Add async signal helpers") Cc: Link: https://patch.msgid.link/20260420061721.3253644-1-tiwai@suse.de Signed-off-by: Takashi Iwai diff --git a/sound/core/misc.c b/sound/core/misc.c index 88d9e1f9a6e9..5aca09edf971 100644 --- a/sound/core/misc.c +++ b/sound/core/misc.c @@ -100,14 +100,18 @@ static LIST_HEAD(snd_fasync_list); static void snd_fasync_work_fn(struct work_struct *work) { struct snd_fasync *fasync; + int signal, poll; spin_lock_irq(&snd_fasync_lock); while (!list_empty(&snd_fasync_list)) { fasync = list_first_entry(&snd_fasync_list, struct snd_fasync, list); list_del_init(&fasync->list); + if (!fasync->on) + continue; + signal = fasync->signal; + poll = fasync->poll; spin_unlock_irq(&snd_fasync_lock); - if (fasync->on) - kill_fasync(&fasync->fasync, fasync->signal, fasync->poll); + kill_fasync(&fasync->fasync, signal, poll); spin_lock_irq(&snd_fasync_lock); } spin_unlock_irq(&snd_fasync_lock); @@ -158,7 +162,10 @@ void snd_fasync_free(struct snd_fasync *fasync) { if (!fasync) return; - fasync->on = 0; + + scoped_guard(spinlock_irq, &snd_fasync_lock) + list_del_init(&fasync->list); + flush_work(&snd_fasync_work); kfree(fasync); }