Re: [PATCH 1/2] coresight: Fix memory leak in acpi_buffer->pointer

On 17/08/2023 09:59, Junhao He wrote:

There are memory leaks reported by kmemleak: ... unreferenced object 0xffff00213c141000 (size 1024): comm "systemd-udevd", pid 2123, jiffies 4294909467 (age 6062.160s) hex dump (first 32 bytes): 04 00 00 00 02 00 00 00 18 10 14 3c 21 00 ff ff ...........<!... 00 00 00 00 00 00 00 00 03 00 00 00 10 00 00 00 ................ backtrace: [<000000004b7c9001>] __kmem_cache_alloc_node+0x2f8/0x348 [<00000000b0fc7ceb>] __kmalloc+0x58/0x108 [<0000000064ff4695>] acpi_os_allocate+0x2c/0x68 [<000000007d57d116>] acpi_ut_initialize_buffer+0x54/0xe0 [<0000000024583908>] acpi_evaluate_object+0x388/0x438 [<0000000017b2e72b>] acpi_evaluate_object_typed+0xe8/0x240 [<000000005df0eac2>] coresight_get_platform_data+0x1b4/0x988 [coresight] ...

The ACPI buffer memory (buf.pointer) should be freed. But the buffer is also used after returning from acpi_get_dsd_graph(). Move the temporary variables buf to acpi_coresight_parse_graph(), and free it before the function return to prevent memory leak.

Fixes: 76ffa5ab5b79 ("coresight: Support for ACPI bindings") Signed-off-by: Junhao He hejunhao3@huawei.com

I confirmed that the error gone. Thanks for the fix.

Reviewed-by: James Clark james.clark@arm.com

---

.../hwtracing/coresight/coresight-platform.c | 40 ++++++++++++------- 1 file changed, 26 insertions(+), 14 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c index 7d7b641c0a71..9d550f5697fa 100644 --- a/drivers/hwtracing/coresight/coresight-platform.c +++ b/drivers/hwtracing/coresight/coresight-platform.c @@ -492,19 +492,18 @@ static inline bool acpi_validate_dsd_graph(const union acpi_object *graph) /* acpi_get_dsd_graph - Find the _DSD Graph property for the given device. */ static const union acpi_object * -acpi_get_dsd_graph(struct acpi_device *adev) +acpi_get_dsd_graph(struct acpi_device *adev, struct acpi_buffer *buf) { int i;

• struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER }; acpi_status status; const union acpi_object *dsd;

status = acpi_evaluate_object_typed(adev->handle, "_DSD", NULL,

• 			    &buf, ACPI_TYPE_PACKAGE);
  

• 			    buf, ACPI_TYPE_PACKAGE);
  

  if (ACPI_FAILURE(status)) return NULL;

• dsd = buf.pointer;

• dsd = buf->pointer;

/* * _DSD property consists tuples { Prop_UUID, Package() } @@ -555,12 +554,12 @@ acpi_validate_coresight_graph(const union acpi_object *cs_graph)

• returns NULL.

*/ static const union acpi_object * -acpi_get_coresight_graph(struct acpi_device *adev) +acpi_get_coresight_graph(struct acpi_device *adev, struct acpi_buffer *buf) { const union acpi_object *graph_list, *graph; int i, nr_graphs;

• graph_list = acpi_get_dsd_graph(adev);

• graph_list = acpi_get_dsd_graph(adev, buf); if (!graph_list) return graph_list;

@@ -661,22 +660,24 @@ static int acpi_coresight_parse_graph(struct device *dev, struct acpi_device *adev, struct coresight_platform_data *pdata) {

• int ret = 0; int i, nlinks; const union acpi_object *graph; struct coresight_connection conn, zero_conn = {}; struct coresight_connection *new_conn;
• struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };

• graph = acpi_get_coresight_graph(adev);

• graph = acpi_get_coresight_graph(adev, &buf); /*
  • There are no graph connections, which is fine for some components.
  • e.g., ETE
  */ if (!graph)

• return 0;
  

• goto free;
  

nlinks = graph->package.elements[2].integer.value; if (!nlinks)

• return 0;
  

• goto free;
  

for (i = 0; i < nlinks; i++) { const union acpi_object *link = &graph->package.elements[3 + i]; @@ -684,17 +685,28 @@ static int acpi_coresight_parse_graph(struct device *dev, conn = zero_conn; dir = acpi_coresight_parse_link(adev, link, &conn);

• if (dir < 0)
  

• 	return dir;
  

• if (dir < 0) {
  

• 	ret = dir;
  

• 	goto free;
  

• }
  

if (dir == ACPI_CORESIGHT_LINK_MASTER) { new_conn = coresight_add_out_conn(dev, pdata, &conn);

• 	if (IS_ERR(new_conn))
  

• 		return PTR_ERR(new_conn);
  

• 	if (IS_ERR(new_conn)) {
  

• 		ret = PTR_ERR(new_conn);
  

• 		goto free;
  

• 	}
  

  } }

• return 0;

+free:

• /*

• * When ACPI fails to alloc a buffer, it will free the buffer
  

• * created via ACPI_ALLOCATE_BUFFER and set to NULL.
  

• * ACPI_FREE can handle NULL pointers, so free it directly.
  

• */
  

• ACPI_FREE(buf.pointer);
• return ret;

} /*