From 369d913b242cae2205471b11b6e33ac368ed33ec Mon Sep 17 00:00:00 2001 From: Fenghua Yu Date: Tue, 25 Sep 2012 11:11:43 -0700 Subject: [PATCH] ACPI: Harden acpi_table_parse_entries() against BIOS bug 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 f336bca7c450..2572d9715bda 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 -- 2.20.1