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 E6B0326A0C6; Tue, 8 Apr 2025 12:04:04 +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=1744113845; cv=none; b=X6eIiLy/cAWyFN06ep3Lg3sXBjrU+z5a3ASez/oLeMAflz8GrsvqR82rkgmqAKVZDAy8/Wfcu0WGMO/i8Jduc/jq9NZuW4pKgLN22nZ7y5xV8bCmUR2a+6bpdGyLzYYN+eCZJlA/YtgiEYAEEOgRftNfgWyRzoGU6a+XAns5tig= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744113845; c=relaxed/simple; bh=+Ui7/qIzHfbX2vg6Hd0cSEC90f7u2DIzuxzp0tfqpSg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gsL9U9oXKyrEQltMgogfjE7NSQOuUgrSDpI8clGpXOgVlIvcWeriYLSMEyKdsMfCsHAyRrCpXMLKYdbrDd57zOAfXxYVLZLeYdg/F9Ny5xVSPOsvM7MMJIzIzbeYQQsXHjK/BTdnRL/w6bDM6ikcSfxSOLGbHVZcSOhg03BNrd8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cgFa3tFv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cgFa3tFv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74E44C4CEEA; Tue, 8 Apr 2025 12:04:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744113844; bh=+Ui7/qIzHfbX2vg6Hd0cSEC90f7u2DIzuxzp0tfqpSg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cgFa3tFv4Ftm0ge15c9erC0fxufVx3QkZWoR51LXI/vfbsVgZbwruo1tR07JLUbep levAj70BT9RTo9u9N/UBSFL8HYjQqZ/JhjgPqNQTo4eysMC8apblWRgdolkfJ5lGEP 7wyD6SK5xC1Vzq4KmbIx4ulNuYx+FsqG80uf7diA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Florent Revest , "Borislav Petkov (AMD)" Subject: [PATCH 5.4 042/154] x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes Date: Tue, 8 Apr 2025 12:49:43 +0200 Message-ID: <20250408104816.620441254@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250408104815.295196624@linuxfoundation.org> References: <20250408104815.295196624@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Florent Revest commit e3e89178a9f4a80092578af3ff3c8478f9187d59 upstream. Currently, load_microcode_amd() iterates over all NUMA nodes, retrieves their CPU masks and unconditionally accesses per-CPU data for the first CPU of each 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=y 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 determining 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 Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/microcode/amd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/cpu/microcode/amd.c +++ b/arch/x86/kernel/cpu/microcode/amd.c @@ -862,7 +862,7 @@ static enum ucode_state load_microcode_a return ret; } - for_each_node(nid) { + for_each_node_with_cpus(nid) { cpu = cpumask_first(cpumask_of_node(nid)); c = &cpu_data(cpu);