[PATCH 4.10 28/69] acpi, nfit, libnvdimm: fix interleave set cookie calculation (64-bit comparison)

Greg Kroah-Hartman
2017-04-19T15:28:01Z

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

commit b03b99a329a14b7302f37c3ea6da3848db41c8c5 upstream.

While reviewing the -stable patch for commit 86ef58a4e35e "nfit,
libnvdimm: fix interleave set cookie calculation" Ben noted:

"This is returning an int, thus it's effectively doing a 32-bit
comparison and not the 64-bit comparison you say is needed."

Update the compare operation to be immune to this integer demotion problem.

Cc: Nicholas Moulin <nicholas.w.moulin@linux.intel.com>
Fixes: 86ef58a4e35e ("nfit, libnvdimm: fix interleave set cookie calculation")
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/acpi/nfit/core.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1617,7 +1617,11 @@ static int cmp_map(const void *m0, const
const struct nfit_set_info_map *map0 = m0;
const struct nfit_set_info_map *map1 = m1;

- return map0->region_offset - map1->region_offset;
+ if (map0->region_offset < map1->region_offset)
+ return -1;
+ else if (map0->region_offset > map1->region_offset)
+ return 1;
+ return 0;
}

/* Retrieve the nth entry referencing this spa */