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 CCC5F2741D3; Fri, 30 May 2025 12:41:39 +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=1748608899; cv=none; b=Wx0R9fA8Mxg4GYaGfCLM2xtiPgbt11n17xyNJQ+y+QA3tFe1yI5kLybS/LXmPW8i+fOlEZTEirprXzxq2vJ26P2oCVBkvwB6RdJD8H9JCvsNluD8G3DlTFNM7IaGnwDomSeVCc8NwmgPPTyQwapITXlgrA6BqZPtS+Z42BuQVUY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748608899; c=relaxed/simple; bh=rjpar9TYqG7jVXukYFvRGIrGJD2KtT6Lt6wPL9nnHE4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=FsyQ74cv5NitzgxTd6x0sQHP5+xQPE4XXZflHLEnHj4/7Obv+eUIbklFQ4qi+WimxI41pClmRXtJn8g9WXoWnvKfKpC2Wx0JYXpCaGWOabvhldN8fpKREemDZbyRgaudlRPMstcm7dVzQZObIGjmHqVFZ4+cRgtl51mzLliTldw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RFpmGXYl; 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="RFpmGXYl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73CADC4CEF0; Fri, 30 May 2025 12:41:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1748608899; bh=rjpar9TYqG7jVXukYFvRGIrGJD2KtT6Lt6wPL9nnHE4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RFpmGXYljb6LwqDSDzFZVHaR6tD1KA49zoRAJQoUEhWY7qoqD82Nr0fGF+UIDC2tr mTWaMsOBIMLf0IdqBP3jxvUY9l30zxofInXBTlXzUIHxbIeo4UXy7M1+hpuH5mXJrj BRD3XfAvyRc9UzepZUz0LP8xVRODohwPt3qlHwG8CS9xZ8MPRKFOdY8hJKYf7pPwLK sHiqJQB365D2hHBZo5Ip68UFBjB1JCgW8yXiHhz+8as8p+2jiqP44Dk0aAi4jczxEy 5u6vVnoq10FQxCoHfyOe/wji7Xd5YUCSbtzMUNz+mGOn6NyNUrpPtQSeufsv4aXwNj yC3AJ3dWswgEg== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Armin Wolf , "Rafael J . Wysocki" , Sasha Levin , rjw@rjwysocki.net, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 5.15 05/11] ACPI: bus: Bail out if acpi_kobj registration fails Date: Fri, 30 May 2025 08:41:25 -0400 Message-Id: <20250530124131.2576650-5-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250530124131.2576650-1-sashal@kernel.org> References: <20250530124131.2576650-1-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 5.15.184 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Armin Wolf [ Upstream commit 94a370fc8def6038dbc02199db9584b0b3690f1a ] The ACPI sysfs code will fail to initialize if acpi_kobj is NULL, together with some ACPI drivers. Follow the other firmware subsystems and bail out if the kobject cannot be registered. Signed-off-by: Armin Wolf Link: https://patch.msgid.link/20250518185111.3560-2-W_Armin@gmx.de Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- **YES** This commit should be backported to stable kernel trees. Here's my extensive analysis: ## Code Change Analysis The commit changes the behavior in `acpi_init()` when `kobject_create_and_add("acpi", firmware_kobj)` fails: **Before:** - If `acpi_kobj` creation fails, only prints a debug message and continues execution - The function proceeds to initialize ACPI subsystems with a NULL `acpi_kobj` - This leads to potential crashes/failures in other ACPI components **After:** - If `acpi_kobj` creation fails, prints an error message and returns `-ENOMEM` - Prevents initialization of ACPI subsystems with a NULL `acpi_kobj` - Follows proper error handling patterns ## Evidence from Kernel Code Investigation From examining the kernel repository, I found multiple critical usages of `acpi_kobj` that would fail catastrophically if it's NULL: 1. **drivers/acpi/sysfs.c:514**: `kobject_create_and_add("tables", acpi_kobj)` - NULL parent causes undefined behavior 2. **drivers/acpi/sysfs.c:924**: `sysfs_create_group(acpi_kobj, &interrupt_stats_attr_group)` - NULL kobject crashes 3. **drivers/acpi/platform_profile.c**: Multiple `sysfs_notify(acpi_kobj, ...)` calls that would crash with NULL 4. **drivers/acpi/platform_profile.c**: `sysfs_create_group(acpi_kobj, &platform_profile_group)` would fail ## Backport Criteria Assessment ✅ **Fixes a real bug**: Yes - prevents crashes when kobject creation fails ✅ **Small and contained**: Yes - only 4 lines changed in one function ✅ **Clear side effects**: Yes - prevents ACPI initialization on memory allocation failure ✅ **No architectural changes**: Yes - just proper error handling ✅ **Critical subsystem**: Yes - ACPI is core kernel infrastructure ✅ **Minimal regression risk**: Yes - only affects rare failure path ✅ **Follows stable rules**: Yes - important bugfix with minimal risk ## Comparison with Historical Examples This commit closely matches **Similar Commit #1** (Status: YES) which also: - Fixed error handling in ACPI initialization code - Added proper cleanup/error handling when kobject operations fail - Was considered suitable for backporting The commit differs significantly from the "NO" examples which were: - Code cleanup/style changes (Similar Commits #2, #3, #4) - Refactoring without fixing actual bugs (Similar Commit #4) ## Risk Assessment **Low Risk**: The change only affects the extremely rare case where `kobject_create_and_add()` fails due to memory allocation failure. In such cases: - **Current behavior**: System continues with broken ACPI, leading to crashes - **New behavior**: ACPI initialization fails cleanly, system may still boot without ACPI ## Conclusion This is a critical bug fix that prevents crashes in ACPI subsystems when memory allocation fails during boot. It transforms undefined behavior/crashes into clean failure handling, making it an ideal candidate for stable backporting. drivers/acpi/bus.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c index 9bc5bc5bc359b..ea63b8f272892 100644 --- a/drivers/acpi/bus.c +++ b/drivers/acpi/bus.c @@ -1335,8 +1335,10 @@ static int __init acpi_init(void) } acpi_kobj = kobject_create_and_add("acpi", firmware_kobj); - if (!acpi_kobj) - pr_debug("%s: kset create error\n", __func__); + if (!acpi_kobj) { + pr_err("Failed to register kobject\n"); + return -ENOMEM; + } init_prmt(); result = acpi_bus_init(); -- 2.39.5