[PATCH 3.16 078/366] xen/acpi: off by one in read_acpi_id()

Ben Hutchings
2018-10-14T23:16:56Z

From: Dan Carpenter <dan.carpenter@oracle.com>

commit c37a3c94775855567b90f91775b9691e10bd2806 upstream.

If acpi_id is == nr_acpi_bits, then we access one element beyond the end
of the acpi_psd[] array or we set one bit beyond the end of the bit map
when we do __set_bit(acpi_id, acpi_id_present);

Fixes: 59a568029181 ("xen/acpi-processor: C and P-state driver that uploads said data to hypervisor.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/xen/xen-acpi-processor.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/xen/xen-acpi-processor.c
+++ b/drivers/xen/xen-acpi-processor.c
@@ -362,9 +362,9 @@ read_acpi_id(acpi_handle handle, u32 lvl
}
/* There are more ACPI Processor objects than in x2APIC or MADT.
* This can happen with incorrect ACPI SSDT declerations. */
- if (acpi_id > nr_acpi_bits) {
- pr_debug("We only have %u, trying to set %u\n",
- nr_acpi_bits, acpi_id);
+ if (acpi_id >= nr_acpi_bits) {
+ pr_debug("max acpi id %u, trying to set %u\n",
+ nr_acpi_bits - 1, acpi_id);
return AE_OK;
}
/* OK, There is a ACPI Processor object */