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 48D772192F2; Tue, 8 Apr 2025 11:40:07 +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=1744112407; cv=none; b=W5b8e7S6t4Y2wEVWMBQz91hn9B8SMNpi0y6TN1jTrZGDw+7BjwHWRzj5NczCxTsDusWNuTJtGJEIGhwBb5MRKKMUKxn2ucxZnyxMeYsC4mrejiL2GfWqFrP+HrypmloZ8eXtD7FunE3FNkPrDSZB/ayas2HpCenVuHZptkXJWzQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744112407; c=relaxed/simple; bh=4z7I+tDEnAQP+1hoWg475y7VeX/qYDOAtrL0vr7E0zc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Av/epaK2mdWPH/7T08kwliIBUBjeNyNZuRd9iKhZ1pbkJd78mUyz80588yoi2WG9cGEUANoljfmsQdi8RYweJqmh13Xs4J8dsjajIBNb3TjsG9PRQSogrX1+q69V75BCpeHB7qWQMP/XVyKEkoysG170qS5pRkvPEjt3Umz18Hc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JB82TKxq; 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="JB82TKxq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA9CAC4CEE5; Tue, 8 Apr 2025 11:40:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744112407; bh=4z7I+tDEnAQP+1hoWg475y7VeX/qYDOAtrL0vr7E0zc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JB82TKxqjXp64vMRXpan5VwVclgwb9nWwyIPWhI0hVbDHDKm8ON5VeD4zfAlIjId7 thd5hGTMFvGqhMSynSexcVg1kLAUWccq8qHcR+zJ4dfb2faDtPbjVob3D5d1nWQgTV qW5kqVVg4xHCrnpSEt0h7H/VD5dj6xjw+/cP7PAQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Florent Revest , "Borislav Petkov (AMD)" Subject: [PATCH 5.15 057/279] x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes Date: Tue, 8 Apr 2025 12:47:20 +0200 Message-ID: <20250408104827.895636727@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250408104826.319283234@linuxfoundation.org> References: <20250408104826.319283234@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 5.15-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 @@ -861,7 +861,7 @@ 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);