From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753261Ab2JGCor (ORCPT ); Sat, 6 Oct 2012 22:44:47 -0400 Received: from mail-qc0-f174.google.com ([209.85.216.174]:35578 "EHLO mail-qc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752536Ab2JGCoo (ORCPT ); Sat, 6 Oct 2012 22:44:44 -0400 From: Len Brown To: linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Fenghua Yu , Len Brown Subject: [PATCH 48/49] ACPI: Harden acpi_table_parse_entries() against BIOS bug Date: Sat, 6 Oct 2012 22:43:18 -0400 Message-Id: <369d913b242cae2205471b11b6e33ac368ed33ec.1349554106.git.len.brown@intel.com> X-Mailer: git-send-email 1.8.0.rc0.18.gf84667d In-Reply-To: <1349577799-566-1-git-send-email-lenb@kernel.org> References: <1349577799-566-1-git-send-email-lenb@kernel.org> In-Reply-To: References: Reply-To: Len Brown Organization: Intel Open Source Technology Center Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Fenghua Yu Parsing acpi table entries may fall into an infinite loop on a buggy BIOS which has entry length=0 in acpi table. Instead of kernel hang with few failure clue which leads to heavy lifting debug effort, this patch hardens kernel boot by booting into non NUMA mode. The debug info left in log buffer helps people identify the issue. Signed-off-by: Fenghua Yu Signed-off-by: Len Brown --- drivers/acpi/tables.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index f336bca7..2572d97 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -240,10 +240,17 @@ acpi_table_parse_entries(char *id, table_end) { if (entry->type == entry_id && (!max_entries || count++ < max_entries)) - if (handler(entry, table_end)) { - early_acpi_os_unmap_memory((char *)table_header, tbl_size); - return -EINVAL; - } + if (handler(entry, table_end)) + goto err; + + /* + * If entry->length is 0, break from this loop to avoid + * infinite loop. + */ + if (entry->length == 0) { + pr_err(PREFIX "[%4.4s:0x%02x] Invalid zero length\n", id, entry_id); + goto err; + } entry = (struct acpi_subtable_header *) ((unsigned long)entry + entry->length); @@ -255,6 +262,9 @@ acpi_table_parse_entries(char *id, early_acpi_os_unmap_memory((char *)table_header, tbl_size); return count; +err: + early_acpi_os_unmap_memory((char *)table_header, tbl_size); + return -EINVAL; } int __init -- 1.8.0.rc0.18.gf84667d