[PATCH] coresight: Fix support for sparsely populated ports

From: Suzuki K Poulose
Date: Thu Apr 09 2020 - 07:05:35 EST

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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, like :

[ 526.110401] ==================================================================
[ 526.117988] BUG: KASAN: slab-out-of-bounds in funnel_enable+0x54/0x1b0
[ 526.124706] Read of size 4 at addr ffffff8135f9549c by task bash/1114
[ 526.131324]
[ 526.132886] CPU: 3 PID: 1114 Comm: bash Tainted: G S 5.4.25 #232
[ 526.140397] Hardware name: Qualcomm Technologies, Inc. SC7180 IDP (DT)
[ 526.147113] Call trace:
[ 526.149653] dump_backtrace+0x0/0x188
[ 526.153431] show_stack+0x20/0x2c
[ 526.156852] dump_stack+0xdc/0x144
[ 526.160370] print_address_description+0x3c/0x494
[ 526.165211] __kasan_report+0x144/0x168
[ 526.169170] kasan_report+0x10/0x18
[ 526.172769] check_memory_region+0x1a4/0x1b4
[ 526.177164] __kasan_check_read+0x18/0x24
[ 526.181292] funnel_enable+0x54/0x1b0
[ 526.185072] coresight_enable_path+0x104/0x198
[ 526.189649] coresight_enable+0x118/0x26c

...

[ 526.237782] Allocated by task 280:
[ 526.241298] __kasan_kmalloc+0xf0/0x1ac
[ 526.245249] kasan_kmalloc+0xc/0x14
[ 526.248849] __kmalloc+0x28c/0x3b4
[ 526.252361] coresight_register+0x88/0x250
[ 526.256587] funnel_probe+0x15c/0x228
[ 526.260365] dynamic_funnel_probe+0x20/0x2c
[ 526.264679] amba_probe+0xbc/0x158
[ 526.268193] really_probe+0x144/0x408
[ 526.271970] driver_probe_device+0x70/0x140

...

[ 526.316810]
[ 526.318364] Freed by task 0:
[ 526.321344] (stack is not available)
[ 526.325024]
[ 526.326580] The buggy address belongs to the object at ffffff8135f95480
[ 526.326580] which belongs to the cache kmalloc-128 of size 128
[ 526.339439] The buggy address is located 28 bytes inside of
[ 526.339439] 128-byte region [ffffff8135f95480, ffffff8135f95500)
[ 526.351399] The buggy address belongs to the page:
[ 526.356342] page:ffffffff04b7e500 refcount:1 mapcount:0 mapping:ffffff814b00c380 index:0x0 compound_mapcount: 0
[ 526.366711] flags: 0x4000000000010200(slab|head)
[ 526.371475] raw: 4000000000010200 ffffffff05034008 ffffffff0501eb08 ffffff814b00c380
[ 526.379435] raw: 0000000000000000 0000000000190019 00000001ffffffff 0000000000000000
[ 526.387393] page dumped because: kasan: bad access detected
[ 526.393128]
[ 526.394681] Memory state around the buggy address:
[ 526.399619] ffffff8135f95380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 526.407046] ffffff8135f95400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 526.414473] >ffffff8135f95480: 04 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 526.421900] ^
[ 526.426029] ffffff8135f95500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 526.433456] ffffff8135f95580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 526.440883] ==================================================================

To keep the code simple, we now track the maximum number of
possible input/output connections to/from this component
@ nr_inport and nr_outport in platform_data, respectively.
Thus the output connections could be sparse and code is
adjusted to skip the unspecified connections.

Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Mike Leach <mike.leach@xxxxxxxxxx>
Reported-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Tested-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
.../hwtracing/coresight/coresight-platform.c | 74 ++++++++++++-------
drivers/hwtracing/coresight/coresight.c | 8 +-
include/linux/coresight.h | 10 ++-
3 files changed, 62 insertions(+), 30 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
index 3c5bee429105..c57373b49b42 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 +225,13 @@ 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 +244,6 @@ 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 +257,6 @@ 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 +285,6 @@ 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 +296,9 @@ 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 +637,11 @@ 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 +687,14 @@ 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 +703,13 @@ 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;
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) {
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 44e552de419c..7f8d2b39aee2 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -90,10 +90,12 @@ union coresight_dev_subtype {
};

/**
- * struct coresight_platform_data - data harvested from the DT specification
- * @nr_inport: number of input ports for this component.
- * @nr_outport: number of output ports for this component.
- * @conns: Array of nr_outport connections from this component
+ * struct coresight_platform_data - data harvested from the firmware
+ * specification.
+ *
+ * @nr_inport: Number of elements for the input connections.
+ * @nr_outport: Number of elements for the output connections.
+ * @conns: Sparse arrray of nr_outport connections from this component.
*/
struct coresight_platform_data {
int nr_inport;
--
2.24.1

Next message: Michael Ellerman: "[GIT PULL] Please pull powerpc/linux.git powerpc-5.7-2 tag"
Previous message: Julia Lawall: "Re: [Cocci] Coccinelle rule for CVE-2019-18683"
Next in thread: Mathieu Poirier: "Re: [PATCH] coresight: Fix support for sparsely populated ports"
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