ACPI / APEI: Fix crash in apei_hest_parse() for acpi=off

After commit 92ef2a2 (ACPI: Change the ordering of PCI root bridge
driver registrarion), acpi_hest_init() is never called for acpi=off
(acpi_disabled), so hest_disable is not set, but hest_tab is NULL,
which causes apei_hest_parse() to crash when it is called from
aer_acpi_firmware_first().

Fix that by making apei_hest_parse() check if hest_tab is not NULL
in addition to checking hest_disable.  Also remove the now useless
acpi_disabled check from apei_hest_parse().

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 1 insertions, 4 deletions

diff --git a/drivers/acpi/apei/hest.c b/drivers/acpi/apei/hest.c
index 7f00cf38098f..f5ef5d54e4ac 100644
--- a/drivers/acpi/apei/hest.c
+++ b/drivers/acpi/apei/hest.c
@@ -89,7 +89,7 @@ int apei_hest_parse(apei_hest_func_t func, void *data)
         struct acpi_hest_header *hest_hdr;
         int i, rc, len;
 
-        if (hest_disable)
+        if (hest_disable || !hest_tab)
                 return -EINVAL;
 
         hest_hdr = (struct acpi_hest_header *)(hest_tab + 1);
@@ -216,9 +216,6 @@ void __init acpi_hest_init(void)
                 return;
         }
 
-        if (acpi_disabled)
-                goto err;
-
         status = acpi_get_table(ACPI_SIG_HEST, 0,
                                 (struct acpi_table_header **)&hest_tab);
         if (status == AE_NOT_FOUND)