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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, stuart hayes <stuart.w.hayes@gmail.com>,
        Jeff Moyer <jmoyer@redhat.com>,
        Dan Williams <dan.j.williams@intel.com>
Subject: [PATCH 4.19 061/103] acpi/nfit: Block function zero DSMs
Date:   Tue, 29 Jan 2019 12:35:38 +0100
Message-Id: <20190129113204.339577731@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Williams <dan.j.williams@intel.com>

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>

---
 drivers/acpi/nfit/core.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1764,6 +1764,13 @@ static int acpi_nfit_add_dimm(struct acp
 		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,