4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vishal Verma <vishal.l.verma@xxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: Lukasz Dorau <lukasz.dorau@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Fixes: efda1b5d87cb ("acpi, nfit, libnvdimm: fix / harden ars_status output length handling")
Signed-off-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Reviewed-by: Keith Busch <keith.busch@xxxxxxxxx>
Signed-of-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/nvdimm/bus.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -748,9 +748,9 @@ u32 nd_cmd_out_size(struct nvdimm *nvdim
* 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;
