4.9-stable review patch. If anyone has any objections, please let me know.
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From: Vishal Verma vishal.l.verma@intel.com
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
--- 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;