acpi/nfit: Block function zero DSMs

BugLink: https://bugs.launchpad.net/bugs/1837664
commit 5e9e38d0db1d29efed1dd4cf9a70115d33521be7 upstream.

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: <stable@vger.kernel.org>
Cc: stuart hayes <stuart.w.hayes@gmail.com>
Fixes: e02fb7264d8a ("nfit: add Microsoft NVDIMM DSM command set...")
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 2ac3d37530f3974bd1a6afadcb439b92fdf5b6ef..a31a898bc9500ea1269ca38fb8b198b68de58a5c 100644 (file)
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1743,6 +1743,13 @@ 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,