Re: [PATCH v2] coresight: Fix support for sparsely populated ports
From: Mathieu Poirier
Date: Thu Apr 16 2020 - 11:50:53 EST
On Tue, Apr 14, 2020 at 02:05:05PM +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@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>
I have applied your patch.
Thanks,
Mathieu
> ---
> Changes since v1:
> - Rebased onto Mathieu's coresight/next tree.
> - Added comments to explain the input port tracking
> ---
> .../hwtracing/coresight/coresight-platform.c | 85 +++++++++++++------
> drivers/hwtracing/coresight/coresight.c | 7 +-
> include/linux/coresight.h | 10 ++-
> 3 files changed, 72 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
> index 4b78e1ac5285..d58dcd0ab514 100644
> --- a/drivers/hwtracing/coresight/coresight-platform.c
> +++ b/drivers/hwtracing/coresight/coresight-platform.c
> @@ -87,6 +87,7 @@ 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 {
> @@ -94,10 +95,16 @@ 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);
>
> @@ -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;
> }
>
> @@ -191,14 +205,12 @@ 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;
> @@ -206,6 +218,7 @@ 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 */
> @@ -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
> @@ -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);
> @@ -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;
> @@ -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))) {
> /*
> @@ -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;
> @@ -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;
> @@ -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;
> }
> }
>
> @@ -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;
> diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
> index 4f10cfa9dc18..f3efbb3b2b4d 100644
> --- a/drivers/hwtracing/coresight/coresight.c
> +++ b/drivers/hwtracing/coresight/coresight.c
> @@ -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? */
> @@ -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) {
> @@ -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) {
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index ccd17304d7bd..e3e9f0e3a878 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -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;
> --
> 2.24.1
>