Re: [PATCH] coresight: Fix support for sparsely populated ports

Hi Suzuki,

On Thu, Apr 09, 2020 at 12:03:16PM +0100, Suzuki K Poulose wrote:

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

---

.../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;
  

How you are using the current ptr as a scratch pad for input port was definitely a brain twister this morning... I would certainly appreciate a richer comment so that I (or anyone else) doesn't have to go through the same process the next time around.

}

} @@ -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.

s/arrray/array

Please rebase your work on my the coresight-next branch. Other than the above this patch looks fine to me.

Thanks, Mathieu

*/ struct coresight_platform_data { int nr_inport; -- 2.24.1