[PATCH] coresight: platform: defer connection counter increment until alloc succeeds

[PATCH] coresight: platform: defer connection counter increment until alloc succeeds

[Jie Gan]

coresight_add_out_conn() increments nr_outconns before calling
devm_krealloc_array() and again before devm_kmalloc(). If either
allocation fails, the counter is already bumped while the corresponding
array entry is NULL or uninitialized garbage.

coresight_add_in_conn() has the same problem with nr_inconns and
devm_krealloc_array().

In both cases the probe returns -ENOMEM, which causes
coresight_get_platform_data() to call coresight_release_platform_data()
for cleanup. That function iterates up to nr_outconns (or nr_inconns)
entries and dereferences each pointer unconditionally, hitting the NULL
or garbage entry and panicking instead of failing gracefully.

Fix by moving the counter increments to after all allocations succeed,
so the struct is always consistent on any error path.

Fixes: 3d4ff657e454 ("coresight: Dynamically add connections")
Fixes: e3f4e68797a9 ("coresight: Store in-connections as well as out-connections")
Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
---
 drivers/hwtracing/coresight/coresight-platform.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
index e337b6e2bf32..93c2d075cad6 100644
--- a/drivers/hwtracing/coresight/coresight-platform.c
+++ b/drivers/hwtracing/coresight/coresight-platform.c
@@ -45,9 +45,8 @@ coresight_add_out_conn(struct device *dev,
 		}
 	}
 
-	pdata->nr_outconns++;
 	pdata->out_conns =
-		devm_krealloc_array(dev, pdata->out_conns, pdata->nr_outconns,
+		devm_krealloc_array(dev, pdata->out_conns, pdata->nr_outconns + 1,
 				    sizeof(*pdata->out_conns), GFP_KERNEL);
 	if (!pdata->out_conns)
 		return ERR_PTR(-ENOMEM);
@@ -63,7 +62,8 @@ coresight_add_out_conn(struct device *dev,
 	 * used right away.
 	 */
 	*conn = *new_conn;
-	pdata->out_conns[pdata->nr_outconns - 1] = conn;
+	pdata->out_conns[pdata->nr_outconns] = conn;
+	pdata->nr_outconns++;
 	return conn;
 }
 EXPORT_SYMBOL_GPL(coresight_add_out_conn);
@@ -86,13 +86,13 @@ int coresight_add_in_conn(struct coresight_connection *out_conn)
 			return 0;
 		}
 
-	pdata->nr_inconns++;
 	pdata->in_conns =
-		devm_krealloc_array(dev, pdata->in_conns, pdata->nr_inconns,
+		devm_krealloc_array(dev, pdata->in_conns, pdata->nr_inconns + 1,
 				    sizeof(*pdata->in_conns), GFP_KERNEL);
 	if (!pdata->in_conns)
 		return -ENOMEM;
-	pdata->in_conns[pdata->nr_inconns - 1] = out_conn;
+	pdata->in_conns[pdata->nr_inconns] = out_conn;
+	pdata->nr_inconns++;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(coresight_add_in_conn);

---
base-commit: e98d21c170b01ddef366f023bbfcf6b31509fa83
change-id: 20260511-fix-ref-count-issue-7c44ce39700f

Best regards,
-- 
Jie Gan <jie.gan@oss.qualcomm.com>