[PATCH v2] power: sequencing: fix an invalid pointer dereference in error path

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

We may end up calling pwrseq_target_free() on a partially initialized
target object whose unit is either NULL or an ERR_PTR(). Avoid
dereferencing invalid memory by adding an appropriate check to
pwrseq_target_free().

Fixes: 249ebf3f65f8 ("power: sequencing: implement the pwrseq core")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-pm/62a3531e-9927-40f8-b587-254a2dfa47ef@stanley.mountain/
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
---
- check for ERR_PTR() in addition to checking for NULL
- only add the check to pwrseq_target_free() as anywhere else unit is
  always set and if it's not then it's another bug that needs fixing

 drivers/power/sequencing/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/power/sequencing/core.c b/drivers/power/sequencing/core.c
index 9c32b07a55e7..0ffc259c6bb6 100644
--- a/drivers/power/sequencing/core.c
+++ b/drivers/power/sequencing/core.c
@@ -212,7 +212,8 @@ pwrseq_target_new(const struct pwrseq_target_data *data)
 
 static void pwrseq_target_free(struct pwrseq_target *target)
 {
-	pwrseq_unit_put(target->unit);
+	if (!IS_ERR_OR_NULL(target->unit))
+		pwrseq_unit_put(target->unit);
 	kfree_const(target->name);
 	kfree(target);
 }
-- 
2.43.0