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coresight: Fix support for sparsely populated ports
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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@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Reported-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Tested-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200518180242.7916-13-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@gregkh
Suzuki K Poulose authored and gregkh committed May 19, 2020
1 parent 1c33c65 commit d375b35
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Showing 3 changed files with 72 additions and 30 deletions.
85 changes: 60 additions & 25 deletions drivers/hwtracing/coresight/coresight-platform.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -87,17 +87,24 @@ 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 {
ep = of_graph_get_next_endpoint(node, ep);
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);

Expand Down Expand Up @@ -137,9 +144,16 @@ 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;
}

Expand Down Expand Up @@ -191,21 +205,20 @@ 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;
struct device_node *rparent = NULL;
struct device_node *rep = NULL;
struct device *rdev = NULL;
struct fwnode_handle *rdev_fwnode;
struct coresight_connection *conn;

do {
/* Parse the local port details */
Expand All @@ -232,6 +245,13 @@ 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
Expand All @@ -244,7 +264,6 @@ 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);
Expand All @@ -258,7 +277,6 @@ 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;
Expand Down Expand Up @@ -287,8 +305,6 @@ 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))) {
/*
Expand All @@ -300,15 +316,9 @@ 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;
Expand Down Expand Up @@ -647,6 +657,16 @@ 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) {
/*
* We are only interested in the port number
* for the input ports at this component.
* Store the port number in child_port.
*/
conn->child_port = fields[0].integer.value;
} else {
/* Invalid direction */
return -EINVAL;
}

return dir;
Expand Down Expand Up @@ -692,10 +712,20 @@ 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);
/*
* We do not track input port connections for a device.
* However we need the highest port number described,
* which can be recorded now and reuse this connection
* record for an output connection. Hence, do not move
* the ptr for input connections
*/
if (ptr->child_port > pdata->nr_inport)
pdata->nr_inport = ptr->child_port;
}
}

Expand All @@ -704,8 +734,13 @@ 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;
Expand Down
7 changes: 6 additions & 1 deletion drivers/hwtracing/coresight/coresight.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1053,6 +1053,9 @@ 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? */
Expand Down Expand Up @@ -1091,6 +1094,8 @@ static int coresight_fixup_device_conns(struct coresight_device *csdev)
for (i = 0; i < csdev->pdata->nr_outport; i++) {
struct coresight_connection *conn = &csdev->pdata->conns[i];

if (!conn->child_fwnode)
continue;
conn->child_dev =
coresight_find_csdev_by_fwnode(conn->child_fwnode);
if (conn->child_dev) {
Expand Down Expand Up @@ -1126,7 +1131,7 @@ 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) {
Expand Down
10 changes: 6 additions & 4 deletions include/linux/coresight.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -100,10 +100,12 @@ 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 array of nr_outport connections from this component.
*/
struct coresight_platform_data {
int nr_inport;
Expand Down

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