[Linux-stm32] [PATCH v2] stm class: Fix a double free in stm_register_device()

[Dan Carpenter]

The put_device(&stm->dev) call will trigger stm_device_release() which
frees "stm" so the vfree(stm) on the next line is a double free.

Fixes: 389b6699a2aa ("stm class: Fix stm device initialization order")
Signed-off-by: Dan Carpenter <dan.carpenter at linaro.org>
---
v2:  My first version introduced a use after free bug.  Thanks Amelie,
     for catching this.

 drivers/hwtracing/stm/core.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 534fbefc7f6a..20895d391562 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -868,8 +868,11 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
 		return -ENOMEM;
 
 	stm->major = register_chrdev(0, stm_data->name, &stm_fops);
-	if (stm->major < 0)
-		goto err_free;
+	if (stm->major < 0) {
+		err = stm->major;
+		vfree(stm);
+		return err;
+	}
 
 	device_initialize(&stm->dev);
 	stm->dev.devt = MKDEV(stm->major, 0);
@@ -913,10 +916,8 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
 err_device:
 	unregister_chrdev(stm->major, stm_data->name);
 
-	/* matches device_initialize() above */
+	/* calls stm_device_release() */
 	put_device(&stm->dev);
-err_free:
-	vfree(stm);
 
 	return err;
 }
-- 
2.42.0