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 73935441037; Mon, 17 Aug 2026 15:19:02 +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=1786979945; cv=none; b=i0NAzMdxKaoSeWzwXBe+OUWUOTsC+Ks/GtWW9o2B/8t5IQLT7tJTx5G6xzQLa7q7asp9/h1YCWWLeVzMF/IYlawg23RlMEFt2SO526x5qa03mqlCfraRkJbfpjz/MyNSB6kqfelmCt6AjeL9EqMWHrrKtZgilciH+OmNEBJyRxU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786979945; c=relaxed/simple; bh=M9NopmatA+XWfITp4rVo4hy9OcsJhtDN87TVIocA8f0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iuVr0ycAQ+WGsJG5aweMQ5kLcrAsZDf0i8+giCebLGPpJNHSSoQWULMENVZrpJu0L9zT2NnG5samg6XJe1M5ZMU6F9L1XpMuNvhKTbX/lYSi8MITXwnf57F0KI0TCEIYlO79QevMT6d3UvgWwqDO4SU4MktTov9pZoed02KRGU4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Uvb7VKun; 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="Uvb7VKun" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D30D41F000E9; Mon, 17 Aug 2026 15:19:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786979942; bh=d0f1N0fwNqDdlbD8SNKeyY8UKx5Qx3aLuivbjlzX53I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Uvb7VKun5M9jZKH2bffLmHqAVS1NC+5gM7ywIOWIwtIK/n6sxulX5CYaDesdZxXlR 7Y08iOtgVvDcRZ5MmRiim8GY1s3WF6flft3dQlRMsEdV2uSYoAtdEfCSRMVw6cOi2Q FG6WgqhOk9FY3CM4vA+xmfBTRYLVdnC2/s0yjl4Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Norbert Szetei , Takashi Iwai Subject: [PATCH 6.1 399/609] ALSA: pcm: wake linked drain waiters on unlink Date: Mon, 17 Aug 2026 15:31:35 +0200 Message-ID: <20260817132557.562536237@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132543.039278408@linuxfoundation.org> References: <20260817132543.039278408@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-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Norbert Szetei commit f495b6c4c8594122918552c9be2b51eb71647cd9 upstream. snd_pcm_drain() on a linked stream parks an on-stack wait entry on the drained peer's runtime->sleep, and after schedule_timeout() removes it only if that peer is still found in the caller's group. If group membership changes during the wait and the sleep ends by signal or timeout (so autoremove_wake_function() does not run), finish_wait() is skipped and snd_pcm_drain() returns with the entry still queued on that stream's sleep list; a later wake_up() then walks a freed stack frame. This is reachable by unlinking either the drained or the draining stream. Unlike the close path (snd_pcm_drop() -> snd_pcm_post_stop()), snd_pcm_unlink() never wakes the sleep queues. Wake every group member under the group lock before the membership change, so a linked drainer is released and drops its entry while the streams are still grouped. The window was opened when snd_pcm_link_rwsem stopped being held across the wait and the removal became conditional on group membership (see Fixes). The later switch to finish_wait() kept that conditional removal, so the signal/timeout case remained. Fixes: f57f3df03a8e ("ALSA: pcm: More fine-grained PCM link locking") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-5 Signed-off-by: Norbert Szetei Link: https://patch.msgid.link/A0705100-D10B-4286-9980-0142ABEEAD51@doyensec.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/pcm_native.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -2352,6 +2352,7 @@ static void relink_to_local(struct snd_p static int snd_pcm_unlink(struct snd_pcm_substream *substream) { + struct snd_pcm_substream *s; struct snd_pcm_group *group; bool nonatomic = substream->pcm->nonatomic; bool do_free = false; @@ -2367,6 +2368,12 @@ static int snd_pcm_unlink(struct snd_pcm group = substream->group; snd_pcm_group_lock_irq(group, nonatomic); + /* release drain waiters before changing membership, else snd_pcm_drain() + * leaves its on-stack wait entry queued on a member's sleep list + */ + snd_pcm_group_for_each_entry(s, substream) + wake_up(&s->runtime->sleep); + relink_to_local(substream); refcount_dec(&group->refs);