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 17BCA2A1AA; Mon, 4 Aug 2025 00:33:34 +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=1754267615; cv=none; b=nAAOxyvWg3tqn4/c6qWhI6Hx0wjTJhi76TliyKVUo2sPgsPEappDc5OQ019V9IqspqKGSzisimHk3cleDPIUhygL4MsJC1z1XS8zeQV81oZkaniFRuvyY20THVHits1TZqwaWBXbRVcgh01bnWJlPRE/KFTrpkJwHE5YzOvRWVI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754267615; c=relaxed/simple; bh=QbbY9LzE3pe7MmocQVzkgRuDJHNQpBut5V80dzTQedw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=JV9/fOmzfb+tQPGHhJiyUugqyDJteFPljr4OhxHmrUKEFhszoC3iDXSWWFgZfui/lAinTzaE3QuFxpyb4xGMGPs0ZiZoPZPtFh445ukTMShjKAtNjRHen9wzY2coIpsTyEynK2DfclspOz2HnDK/ZPf36+uAsVoDeSNPY8ZQ6zQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=T/JQ//Cs; 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="T/JQ//Cs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CEB59C4CEEB; Mon, 4 Aug 2025 00:33:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754267614; bh=QbbY9LzE3pe7MmocQVzkgRuDJHNQpBut5V80dzTQedw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T/JQ//CsP3KDTVRDdWw0wkH2Md06+kXFhU8KCBHIjUCsDo9HNou1hQpJJ6jSPUqWN bs8VCGKKXtRXFTBhBEz6nNBFEBDZYLXXl5K4nh4dFiNG0yG5d38GasUhc7aiiGwUc9 IPN9YGp4RyvjoibxQtwsJIbALWAxYZc1AAXu4AIdN3fWmIbrEHRMx5dkdMWxbS5ZCu g7kXOp7/Spl6uH34/MiMsnq6rXdYq4s/etB/BLRn1J70t/U8RTKmTZcBClT5ttkLwg khfIY4Ycb12q8+oroBVRlydRuvNuZsjShSPZMdM85qJqgK2Tk4I2TLVMp9hycc1RU/ mEUtSm7RQh21A== 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 6.12 55/69] ASoC: core: Check for rtd == NULL in snd_soc_remove_pcm_runtime() Date: Sun, 3 Aug 2025 20:31:05 -0400 Message-Id: <20250804003119.3620476-55-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250804003119.3620476-1-sashal@kernel.org> References: <20250804003119.3620476-1-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 6.12.41 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 e3c8d4f20b9c..4ac870c2dafa 100644 --- a/sound/soc/soc-core.c +++ b/sound/soc/soc-core.c @@ -1138,6 +1138,9 @@ static int snd_soc_compensate_channel_connection_map(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); /* -- 2.39.5