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 --- 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;