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 07C901BD01D; Mon, 4 Aug 2025 00:41:57 +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=1754268117; cv=none; b=MJX4R9aERmrF1EqBAvqpUvf5E8BUgWsWfVdoSrQtA1MCP21l75LkwCE/IsnOwFU7qJZwOjVEAJ85g0TYey7D3LzCeO4P/GNecBTqhJHtYCZkyC16iVHwPE/DDy4WpfuJhvBGjMWBKmFtck/5ean0mBaEBcfsNvHGecga7hRv6nc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754268117; c=relaxed/simple; bh=5SPgjHDGfzDR2tO0FBVO21SYDBBXEJhJm/OQUnOxklM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=myz8ijPqvLfN5cU81H5NT1rbzBFUO0bijBvqzYT3Q089GiLIkGEDD7oagAZ6rnTw7hVjkpW0Ll2AVuyNJlxJloXoWQmGWXA6g4juB4W7l+EGeGdmNfTucABIPlo9HJVaK74m5CXMmx3jrSyaH+KQ2i+1LWE7jQdh3GCNU1Gpd9s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=B3cVJmiV; 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="B3cVJmiV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3647C4CEEB; Mon, 4 Aug 2025 00:41:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754268116; bh=5SPgjHDGfzDR2tO0FBVO21SYDBBXEJhJm/OQUnOxklM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=B3cVJmiVc0m1lOmSdUfxL9KrNkYgu1zwgsvKraxVDVk44HXsy8mzVXgNKxd1EjBvV iA6rsio5ahi1d2a0T2G10Go/o9XTdhszHIBsbrP76KuJQJLGAwKBNsHvHVNPN6HFpP xaF1sH9Gmpa9XhF7r1JeFS9oFhifCTDuLMVubLkZbx/hCD9srP9mVANv0E+Xx/iHc7 20I7ICaXj9eazM/Il4uON+u4rlwKb0II18IZbCONm/9GRwgKGqVJzp2X+U9cxQ7njF evuvgL7cPRGtrMpSESawyZn4Z9GwqDv8B+2xwpPAv1c7XXgBputv75qyv51g5WFkgx 0PdSAxoi2IEpw== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Peter Ujfalusi , Bard Liao , Ranjani Sridharan , Liam Girdwood , Kai Vehmanen , Mark Brown , Sasha Levin , lgirdwood@gmail.com, linux-sound@vger.kernel.org Subject: [PATCH AUTOSEL 5.10 28/39] ASoC: core: Check for rtd == NULL in snd_soc_remove_pcm_runtime() Date: Sun, 3 Aug 2025 20:40:30 -0400 Message-Id: <20250804004041.3628812-28-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250804004041.3628812-1-sashal@kernel.org> References: <20250804004041.3628812-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.10.240 Content-Transfer-Encoding: 8bit From: Peter Ujfalusi [ Upstream commit 2d91cb261cac6d885954b8f5da28b5c176c18131 ] snd_soc_remove_pcm_runtime() might be called with rtd == NULL which will leads to null pointer dereference. This was reproduced with topology loading and marking a link as ignore due to missing hardware component on the system. On module removal the soc_tplg_remove_link() would call snd_soc_remove_pcm_runtime() with rtd == NULL since the link was ignored, no runtime was created. Signed-off-by: Peter Ujfalusi Reviewed-by: Bard Liao Reviewed-by: Ranjani Sridharan Reviewed-by: Liam Girdwood Reviewed-by: Kai Vehmanen Link: https://patch.msgid.link/20250619084222.559-3-peter.ujfalusi@linux.intel.com Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: **YES** This commit should be backported to stable kernel trees. The analysis reveals this is a critical NULL pointer dereference fix that prevents kernel crashes. **Key reasons for backporting:** 1. **Fixes a Real Crash**: The commit adds a NULL check to prevent a kernel panic that occurs when `snd_soc_remove_pcm_runtime()` is called with `rtd == NULL`. The code change shows this clearly: ```c + if (!rtd) + return; ``` Without this check, the subsequent line `snd_soc_card_remove_dai_link(card, rtd->dai_link)` would dereference NULL. 2. **Minimal and Safe Fix**: The change is extremely small (3 lines) and defensive - it simply adds a NULL check with early return. This follows the stable kernel rule of minimal, contained fixes. 3. **Affects Production Systems**: The commit message indicates this occurs during topology loading when hardware components are missing - a real-world scenario. The issue manifests on module removal when `soc_tplg_remove_link()` calls the function with NULL. 4. **Well-Reviewed**: The commit has 5 Reviewed-by tags from Intel ASoC maintainers, indicating thorough review and consensus on the fix. 5. **No Side Effects**: The fix has no architectural changes or new features - it purely adds defensive programming to prevent crashes. The function already had EXPORT_SYMBOL_GPL, indicating it's part of the kernel API that could be called from various contexts. This is exactly the type of commit stable trees want: a small, obvious fix for a real crash scenario with no risk of regression. sound/soc/soc-core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c index e9da95ebccc8..1120d669fe2e 100644 --- a/sound/soc/soc-core.c +++ b/sound/soc/soc-core.c @@ -958,6 +958,9 @@ static int soc_dai_link_sanity_check(struct snd_soc_card *card, void snd_soc_remove_pcm_runtime(struct snd_soc_card *card, struct snd_soc_pcm_runtime *rtd) { + if (!rtd) + return; + lockdep_assert_held(&client_mutex); /* release machine specific resources */ -- 2.39.5