Re: [RFC PATCH] coresight: dynamic-replicator: Fix handling of multiple connections

From: Sai Prakash Ranjan
Date: Thu Apr 09 2020 - 03:51:39 EST

Hi Suzuki,

On 2020-04-09 04:13, Suzuki K Poulose wrote:
On Tue, Apr 07, 2020 at 08:48:54PM +0530, Sai Prakash Ranjan wrote:

Please find the untested patch below.

---8>---

[untested] coresight: Fix support for sparse port numbers

On some systems the firmware may not describe all the ports
connected to a component (e.g, for security reasons). This
could be especially problematic for "funnels" where we could
end up in modifying memory beyond the allocated space for
refcounts.

e.g, for a funnel with input ports listed 0, 3, 5, nr_inport = 3.
However the we could access refcnts[5] while checking for
references.

Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
.../hwtracing/coresight/coresight-platform.c | 74 ++++++++++++-------
drivers/hwtracing/coresight/coresight.c | 8 +-
2 files changed, 56 insertions(+), 26 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-platform.c
b/drivers/hwtracing/coresight/coresight-platform.c
index 3c5bee429105..1c610d6e944b 100644
--- a/drivers/hwtracing/coresight/coresight-platform.c
+++ b/drivers/hwtracing/coresight/coresight-platform.c
@@ -67,6 +67,7 @@ static void of_coresight_get_ports_legacy(const
struct device_node *node,
int *nr_inport, int *nr_outport)
{
struct device_node *ep = NULL;
+ struct of_endpoint endpoint;
int in = 0, out = 0;

do {
@@ -74,10 +75,16 @@ static void of_coresight_get_ports_legacy(const
struct device_node *node,
if (!ep)
break;

- if (of_coresight_legacy_ep_is_input(ep))
- in++;
- else
- out++;
+ if (of_graph_parse_endpoint(ep, &endpoint))
+ continue;
+
+ if (of_coresight_legacy_ep_is_input(ep)) {
+ in = (endpoint.port + 1 > in) ?
+ endpoint.port + 1 : in;
+ } else {
+ out = (endpoint.port + 1) > out ?
+ endpoint.port + 1 : out;
+ }

} while (ep);

@@ -117,9 +124,16 @@ of_coresight_count_ports(struct device_node *port_parent)
{
int i = 0;
struct device_node *ep = NULL;
+ struct of_endpoint endpoint;
+
+ while ((ep = of_graph_get_next_endpoint(port_parent, ep))) {
+ /* Defer error handling to parsing */
+ if (of_graph_parse_endpoint(ep, &endpoint))
+ continue;
+ if (endpoint.port + 1 > i)
+ i = endpoint.port + 1;
+ }

- while ((ep = of_graph_get_next_endpoint(port_parent, ep)))
- i++;
return i;
}

@@ -171,14 +185,12 @@ static int of_coresight_get_cpu(struct device *dev)
* Parses the local port, remote device name and the remote port.
*
* Returns :
- * 1 - If the parsing is successful and a connection record
- * was created for an output connection.
* 0 - If the parsing completed without any fatal errors.
* -Errno - Fatal error, abort the scanning.
*/
static int of_coresight_parse_endpoint(struct device *dev,
struct device_node *ep,
- struct coresight_connection *conn)
+ struct coresight_platform_data *pdata)
{
int ret = 0;
struct of_endpoint endpoint, rendpoint;
@@ -186,6 +198,7 @@ static int of_coresight_parse_endpoint(struct device *dev,
struct device_node *rep = NULL;
struct device *rdev = NULL;
struct fwnode_handle *rdev_fwnode;
+ struct coresight_connection *conn;

do {
/* Parse the local port details */
@@ -212,6 +225,12 @@ static int of_coresight_parse_endpoint(struct device *dev,
break;
}

+ conn = &pdata->conns[endpoint.port];
+ if (conn->child_fwnode) {
+ dev_warn(dev, "Duplicate output port %d\n", endpoint.port);
+ ret = -EINVAL;
+ break;
+ }
conn->outport = endpoint.port;
/*
* Hold the refcount to the target device. This could be
@@ -224,7 +243,6 @@ static int of_coresight_parse_endpoint(struct device *dev,
conn->child_fwnode = fwnode_handle_get(rdev_fwnode);
conn->child_port = rendpoint.port;
/* Connection record updated */
- ret = 1;
} while (0);

of_node_put(rparent);
@@ -238,7 +256,6 @@ static int of_get_coresight_platform_data(struct
device *dev,
struct coresight_platform_data *pdata)
{
int ret = 0;
- struct coresight_connection *conn;
struct device_node *ep = NULL;
const struct device_node *parent = NULL;
bool legacy_binding = false;
@@ -267,8 +284,6 @@ static int of_get_coresight_platform_data(struct
device *dev,
dev_warn_once(dev, "Uses obsolete Coresight DT bindings\n");
}

- conn = pdata->conns;
-
/* Iterate through each output port to discover topology */
while ((ep = of_graph_get_next_endpoint(parent, ep))) {
/*
@@ -280,15 +295,9 @@ static int of_get_coresight_platform_data(struct
device *dev,
if (legacy_binding && of_coresight_legacy_ep_is_input(ep))
continue;

- ret = of_coresight_parse_endpoint(dev, ep, conn);
- switch (ret) {
- case 1:
- conn++; /* Fall through */
- case 0:
- break;
- default:
+ ret = of_coresight_parse_endpoint(dev, ep, pdata);
+ if (ret)
return ret;
- }
}

return 0;
@@ -627,6 +636,11 @@ static int acpi_coresight_parse_link(struct
acpi_device *adev,
* coresight_remove_match().
*/
conn->child_fwnode = fwnode_handle_get(&r_adev->fwnode);
+ } else if (dir == ACPI_CORESIGHT_LINK_SLAVE) {
+ conn->child_port = fields[0].integer.value;
+ } else {
+ /* Invalid direction */
+ return -EINVAL;
}

return dir;
@@ -672,10 +686,14 @@ static int acpi_coresight_parse_graph(struct
acpi_device *adev,
return dir;

if (dir == ACPI_CORESIGHT_LINK_MASTER) {
- pdata->nr_outport++;
+ if (ptr->outport > pdata->nr_outport)
+ pdata->nr_outport = ptr->outport;
ptr++;
} else {
- pdata->nr_inport++;
+ WARN_ON(pdata->nr_inport == ptr->child_port);
+ /* Do not move the ptr for input connections */
+ if (ptr->child_port > pdata->nr_inport)
+ pdata->nr_inport = ptr->child_port;
}
}

@@ -684,8 +702,13 @@ static int acpi_coresight_parse_graph(struct
acpi_device *adev,
return rc;

/* Copy the connection information to the final location */
- for (i = 0; i < pdata->nr_outport; i++)
- pdata->conns[i] = conns[i];
+ for (i = 0; conns + i < ptr; i++) {
+ int port = conns[i].outport;
+
+ /* Duplicate output port */
+ WARN_ON(pdata->conns[port].child_fwnode);
+ pdata->conns[port] = conns[i];
+ }

devm_kfree(&adev->dev, conns);
return 0;
@@ -787,6 +810,7 @@ coresight_get_platform_data(struct device *dev)
goto error;

pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+ pdata->nr_outport = pdata->nr_inport = -1;
if (!pdata) {
ret = -ENOMEM;
goto error;
diff --git a/drivers/hwtracing/coresight/coresight.c
b/drivers/hwtracing/coresight/coresight.c
index ef20f74c85fa..f07bc0a7ab88 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -990,6 +990,9 @@ static int coresight_orphan_match(struct device
*dev, void *data)
for (i = 0; i < i_csdev->pdata->nr_outport; i++) {
conn = &i_csdev->pdata->conns[i];

+ /* Skip the port if FW doesn't describe it */
+ if (!conn->child_fwnode)
+ continue;
/* We have found at least one orphan connection */
if (conn->child_dev == NULL) {
/* Does it match this newly added device? */
@@ -1029,6 +1032,9 @@ static void coresight_fixup_device_conns(struct
coresight_device *csdev)
struct coresight_connection *conn = &csdev->pdata->conns[i];
struct device *dev = NULL;

+ if (!conn->child_fwnode)
+ continue;
+
dev = bus_find_device_by_fwnode(&coresight_bustype, conn->child_fwnode);
if (dev) {
conn->child_dev = to_coresight_device(dev);
@@ -1061,7 +1067,7 @@ static int coresight_remove_match(struct device
*dev, void *data)
for (i = 0; i < iterator->pdata->nr_outport; i++) {
conn = &iterator->pdata->conns[i];

- if (conn->child_dev == NULL)
+ if (conn->child_dev == NULL || conn->child_fwnode == NULL)
continue;

if (csdev->dev.fwnode == conn->child_fwnode) {


Thanks Suzuki, I don't see the KASAN warning anymore with this patch.
But somehow tmc_etr probe fails with error -12(ENOMEM).

Thanks,
Sai

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