From nobody Sun Feb 8 07:22:16 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 34C37227EA0; Mon, 10 Mar 2025 15:17:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741619870; cv=none; b=KGICZMhZhvKd96YB53Z0fZ33MekjzodOImj89HeAv2cc+Ta+jgLT0V7YUfJXI80EYkS4a53eI8dh2uAwZa+EEw8Mcs32Sk4hmU/ZpyZdsr70zAw8zbc8TQxvygkzmkR6q9fRy9miwUgioS287j0e4X48ofrmfTxWnyHubAsId3w= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741619870; c=relaxed/simple; bh=cq5Im/NgOcTZ4rtPa09PGi4z5bXY7vuDuSLx3ZWUD2Q=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=nDldyR4z+86hAnkuDy/giQ8PwJab25twEr+9B7y7yIFuiIEiAic5SJJ4WcMvyVMqYy71h9SZ7dW1XQSgm8JH0a57p2mGP29oONHncl57p2t6jAcgVL0lf4gbrSEh55oUsa+BJKWuQTXveW2PxTCfY3lwJWW+e9PLnJCFB4V2a0w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=kbB96ZpT; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=GtkcfSU2; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="kbB96ZpT"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="GtkcfSU2" Date: Mon, 10 Mar 2025 15:17:43 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1741619867; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kjCXVwpRpL1HkRl3NKPzVuAOudC0kOAalJB1yrlrCZE=; b=kbB96ZpTbWOWEtTRHu/8OmDeRE+k8DuRxNLyzRNxwveydC5UDjliZOzmkXhaevffLF541u pnwWnCP64sQ31aXJfdkgKPDhN1VEZdLeI4Q6wpsoEbOhm0ARd/lIGZraW9SZARHc9h4HZy qaEBz4m4AAO+YnOMGbsde+60vfok6Cws3XY3VQmMp+RfmPAow2WWRpmhCe4yXUYzFy6DX/ 0YdrP+CIhJ5SK8/HRZZ6HB7SL2nxcQ349tbe19I35SrQDoUfF68qXV+ywZw0LlIdFFc4MS E+H9PHyKTyRJwBGFKYm9B3su0jKYble22iYcWrYe6H9zdP5336JymGvd/+FmrQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1741619867; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kjCXVwpRpL1HkRl3NKPzVuAOudC0kOAalJB1yrlrCZE=; b=GtkcfSU28f+3GgA4ByOMml9NAr9hZfj5wacArlLtZxkvKkZH1mHxS74f5rMDmqc8BTNDf2 c/KZQCIIs8s0gQAg== From: "tip-bot2 for Florent Revest" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes Cc: Florent Revest , "Borislav Petkov (AMD)" , stable@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250310144243.861978-1-revest@chromium.org> References: <20250310144243.861978-1-revest@chromium.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <174161986360.14745.5442918704046363367.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/urgent branch of tip: Commit-ID: e3e89178a9f4a80092578af3ff3c8478f9187d59 Gitweb: https://git.kernel.org/tip/e3e89178a9f4a80092578af3ff3c8478f= 9187d59 Author: Florent Revest AuthorDate: Mon, 10 Mar 2025 15:42:43 +01:00 Committer: Borislav Petkov (AMD) CommitterDate: Mon, 10 Mar 2025 16:02:54 +01:00 x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes Currently, load_microcode_amd() iterates over all NUMA nodes, retrieves the= ir CPU masks and unconditionally accesses per-CPU data for the first CPU of ea= ch mask. According to Documentation/admin-guide/mm/numaperf.rst: "Some memory may share the same node as a CPU, and others are provided as memory only nodes." Therefore, some node CPU masks may be empty and wouldn't have a "first CPU". On a machine with far memory (and therefore CPU-less NUMA nodes): - cpumask_of_node(nid) is 0 - cpumask_first(0) is CONFIG_NR_CPUS - cpu_data(CONFIG_NR_CPUS) accesses the cpu_info per-CPU array at an index that is 1 out of bounds This does not have any security implications since flashing microcode is a privileged operation but I believe this has reliability implications by potentially corrupting memory while flashing a microcode update. When booting with CONFIG_UBSAN_BOUNDS=3Dy on an AMD machine that flashes a microcode update. I get the following splat: UBSAN: array-index-out-of-bounds in arch/x86/kernel/cpu/microcode/amd.c:X= :Y index 512 is out of range for type 'unsigned long[512]' [...] Call Trace: dump_stack __ubsan_handle_out_of_bounds load_microcode_amd request_microcode_amd reload_store kernfs_fop_write_iter vfs_write ksys_write do_syscall_64 entry_SYSCALL_64_after_hwframe Change the loop to go over only NUMA nodes which have CPUs before determini= ng whether the first CPU on the respective node needs microcode update. [ bp: Massage commit message, fix typo. ] Fixes: 7ff6edf4fef3 ("x86/microcode/AMD: Fix mixed steppings support") Signed-off-by: Florent Revest Signed-off-by: Borislav Petkov (AMD) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250310144243.861978-1-revest@chromium.org --- arch/x86/kernel/cpu/microcode/amd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/micr= ocode/amd.c index c69b1bc..138689b 100644 --- a/arch/x86/kernel/cpu/microcode/amd.c +++ b/arch/x86/kernel/cpu/microcode/amd.c @@ -1074,7 +1074,7 @@ static enum ucode_state load_microcode_amd(u8 family,= const u8 *data, size_t siz if (ret !=3D UCODE_OK) return ret; =20 - for_each_node(nid) { + for_each_node_with_cpus(nid) { cpu =3D cpumask_first(cpumask_of_node(nid)); c =3D &cpu_data(cpu);