ASoC: Intel: Skylake: Check for NHLT ACPI header signature

In certain buggy BIOS acpi_evaluate_dsm() may not return the correct
NHLT table, so check the NHLT table header signature before accessing
it.

Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
Signed-off-by: Guneshwor Singh <guneshwor.o.singh@intel.com>
Acked-By: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/intel/skylake/skl-nhlt.c b/sound/soc/intel/skylake/skl-nhlt.c
index e7d766d..d14c50a 100644 (file)
--- a/sound/soc/intel/skylake/skl-nhlt.c
+++ b/sound/soc/intel/skylake/skl-nhlt.c
@@ -20,6 +20,8 @@
 #include <linux/pci.h>
 #include "skl.h"
 
+#define NHLT_ACPI_HEADER_SIG   "NHLT"
+
 /* Unique identification for getting NHLT blobs */
 static guid_t osc_guid =
        GUID_INIT(0xA69F886E, 0x6CEB, 0x4594,
@@ -45,6 +47,13 @@ struct nhlt_acpi_table *skl_nhlt_init(struct device *dev)
                                memremap(nhlt_ptr->min_addr, nhlt_ptr->length,
                                MEMREMAP_WB);
                ACPI_FREE(obj);
+               if (nhlt_table && (strncmp(nhlt_table->header.signature,
+                                       NHLT_ACPI_HEADER_SIG,
+                                       strlen(NHLT_ACPI_HEADER_SIG)) != 0)) {
+                       memunmap(nhlt_table);
+                       dev_err(dev, "NHLT ACPI header signature incorrect\n");
+                       return NULL;
+               }
                return nhlt_table;
        }