From: Vishal Verma <vishal.l.verma@intel.com>
Date: Fri, 10 Aug 2018 19:23:15 +0000 (-0600)
Subject: libnvdimm: fix ars_status output length calculation
X-Git-Tag: MMI-QSB30.62-17~983^2~71^2~10
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c8d875b471b6f0304d5d85d0c33c58374b1d78d7;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git

libnvdimm: fix ars_status output length calculation

commit 286e87718103acdf85f4ed323a37e4839a8a7c05 upstream.

Commit efda1b5d87cb ("acpi, nfit, libnvdimm: fix / harden ars_status output length handling")
Introduced additional hardening for ambiguity in the ACPI spec for
ars_status output sizing. However, it had a couple of cases mixed up.
Where it should have been checking for (and returning) "out_field[1] -
4" it was using "out_field[1] - 8" and vice versa.

This caused a four byte discrepancy in the buffer size passed on to
the command handler, and in some cases, this caused memory corruption
like:

  ./daxdev-errors.sh: line 76: 24104 Aborted   (core dumped) ./daxdev-errors $busdev $region
  malloc(): memory corruption
  Program received signal SIGABRT, Aborted.
  [...]
  #5  0x00007ffff7865a2e in calloc () from /lib64/libc.so.6
  #6  0x00007ffff7bc2970 in ndctl_bus_cmd_new_ars_status (ars_cap=ars_cap@entry=0x6153b0) at ars.c:136
  #7  0x0000000000401644 in check_ars_status (check=0x7fffffffdeb0, bus=0x604c20) at daxdev-errors.c:144
  #8  test_daxdev_clear_error (region_name=<optimized out>, bus_name=<optimized out>)
      at daxdev-errors.c:332

Cc: <stable@vger.kernel.org>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Lukasz Dorau <lukasz.dorau@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Fixes: efda1b5d87cb ("acpi, nfit, libnvdimm: fix / harden ars_status output length handling")
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-of-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 2fffd42767c7..fb5ab5812a22 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -808,9 +808,9 @@ u32 nd_cmd_out_size(struct nvdimm *nvdimm, int cmd,
 		 * overshoots the remainder by 4 bytes, assume it was
 		 * including 'status'.
 		 */
-		if (out_field[1] - 8 == remainder)
+		if (out_field[1] - 4 == remainder)
 			return remainder;
-		return out_field[1] - 4;
+		return out_field[1] - 8;
 	} else if (cmd == ND_CMD_CALL) {
 		struct nd_cmd_pkg *pkg = (struct nd_cmd_pkg *) in_field;