acpi/nfit: Block function zero DSMs

In preparation for using function number 0 as an error value, prevent it from being considered a valid function value by acpi_nfit_ctl(). Cc: <[email protected]> Cc: stuart hayes <[email protected]> Fixes: e02fb72 ("nfit: add Microsoft NVDIMM DSM command set...") Reported-by: Jeff Moyer <[email protected]> Reviewed-by: Jeff Moyer <[email protected]> Signed-off-by: Dan Williams <[email protected]>
tomthink · Jan 21, 2019 · 5e9e38d · 5e9e38d
1 parent 1cd7386
commit 5e9e38d
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
@@ -1867,6 +1867,13 @@ static int acpi_nfit_add_dimm(struct acpi_nfit_desc *acpi_desc,
 		return 0;
 	}
 
+	/*
+	 * Function 0 is the command interrogation function, don't
+	 * export it to potential userspace use, and enable it to be
+	 * used as an error value in acpi_nfit_ctl().
+	 */
+	dsm_mask &= ~1UL;
+
 	guid = to_nfit_uuid(nfit_mem->family);
 	for_each_set_bit(i, &dsm_mask, BITS_PER_LONG)
 		if (acpi_check_dsm(adev_dimm->handle, guid,