[PATCH 4.8 18/33] acpi, nfit: validate ars_status output buffer size

From: Greg Kroah-Hartman
Date: Tue Dec 13 2016 - 12:21:59 EST


4.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Dan Williams <dan.j.williams@xxxxxxxxx>

commit 82aa37cf09867c5e2c0326649d570e5b25c1189a upstream.

If an ARS Status command returns truncated output, do not process
partial records or otherwise consume non-status fields.

Fixes: 0caeef63e6d2 ("libnvdimm: Add a poison list and export badblocks")
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/acpi/nfit/core.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)

--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -146,7 +146,8 @@ static int xlat_status(void *buf, unsign
* then just continue with the returned results.
*/
if (status == NFIT_ARS_STATUS_INTR) {
- if (ars_status->flags & NFIT_ARS_F_OVERFLOW)
+ if (ars_status->out_length >= 40 && (ars_status->flags
+ & NFIT_ARS_F_OVERFLOW))
return -ENOSPC;
return 0;
}
@@ -1858,19 +1859,32 @@ static int ars_get_status(struct acpi_nf
return cmd_rc;
}

-static int ars_status_process_records(struct nvdimm_bus *nvdimm_bus,
+static int ars_status_process_records(struct acpi_nfit_desc *acpi_desc,
struct nd_cmd_ars_status *ars_status)
{
+ struct nvdimm_bus *nvdimm_bus = acpi_desc->nvdimm_bus;
int rc;
u32 i;

+ /*
+ * First record starts at 44 byte offset from the start of the
+ * payload.
+ */
+ if (ars_status->out_length < 44)
+ return 0;
for (i = 0; i < ars_status->num_records; i++) {
+ /* only process full records */
+ if (ars_status->out_length
+ < 44 + sizeof(struct nd_ars_record) * (i + 1))
+ break;
rc = nvdimm_bus_add_poison(nvdimm_bus,
ars_status->records[i].err_address,
ars_status->records[i].length);
if (rc)
return rc;
}
+ if (i < ars_status->num_records)
+ dev_warn(acpi_desc->dev, "detected truncated ars results\n");

return 0;
}
@@ -2123,8 +2137,7 @@ static int acpi_nfit_query_poison(struct
if (rc < 0 && rc != -ENOSPC)
return rc;

- if (ars_status_process_records(acpi_desc->nvdimm_bus,
- acpi_desc->ars_status))
+ if (ars_status_process_records(acpi_desc, acpi_desc->ars_status))
return -ENOMEM;

return 0;