From 1c0d9b1c31d19d3aa90296a184e4624545d7d1ee Mon Sep 17 00:00:00 2001 From: Ross Lagerwall Date: Mon, 28 Jan 2019 10:04:23 +0000 Subject: [PATCH] ACPI: APEI: Fix possible out-of-bounds access to BERT region Check that the length recorded in the generic error status block is within the region before checking the contents of the region itself. Otherwise it may result in an out-of-bounds access if the system firmware has generated a status block with an invalid length (larger than the mapped region). Also move the block_status check so that it only happens after the block has been verified to be within the mapped region. Signed-off-by: Ross Lagerwall Acked-by: Borislav Petkov Tested-by: Tyler Baicar Signed-off-by: Rafael J. Wysocki --- drivers/acpi/apei/bert.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-) diff --git a/drivers/acpi/apei/bert.c b/drivers/acpi/apei/bert.c index 12771fc..0d948d0 100644 --- a/drivers/acpi/apei/bert.c +++ b/drivers/acpi/apei/bert.c @@ -42,15 +42,7 @@ static void __init bert_print_all(struct acpi_bert_region *region, int remain = region_len; u32 estatus_len; - if (!estatus->block_status) - return; - - while (remain > sizeof(struct acpi_bert_region)) { - if (cper_estatus_check(estatus)) { - pr_err(FW_BUG "Invalid error record.\n"); - return; - } - + while (remain >= sizeof(struct acpi_bert_region)) { estatus_len = cper_estatus_len(estatus); if (remain < estatus_len) { pr_err(FW_BUG "Truncated status block (length: %u).\n", @@ -58,6 +50,15 @@ static void __init bert_print_all(struct acpi_bert_region *region, return; } + /* No more error records. */ + if (!estatus->block_status) + return; + + if (cper_estatus_check(estatus)) { + pr_err(FW_BUG "Invalid error record.\n"); + return; + } + pr_info_once("Error records from previous boot:\n"); cper_estatus_print(KERN_INFO HW_ERR, estatus); @@ -70,10 +71,6 @@ static void __init bert_print_all(struct acpi_bert_region *region, estatus->block_status = 0; estatus = (void *)estatus + estatus_len; - /* No more error records. */ - if (!estatus->block_status) - return; - remain -= estatus_len; } } -- 2.7.4