On 08/10/2018 12:23 PM, Vishal Verma wrote:
> 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>
Applied.
> ---
> drivers/nvdimm/bus.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
> index 27902a8799b1..8aae6dcc839f 100644
> --- a/drivers/nvdimm/bus.c
> +++ b/drivers/nvdimm/bus.c
> @@ -812,9 +812,9 @@ 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;
>
>
