[PATCH objtool/urgent] klp-build: Fix memory leak when enabling the generated livepatch fails

[Yafang Shao <laoar.shao@gmail.com>]

The klp-build generated livepatch module allocates the patch structure,
the array of objects, and the per-object arrays of functions with
kzalloc() in livepatch_mod_init().

The result of klp_enable_patch() is returned directly. It bypasses
the err_free_objs cleanup path when the call fails. As a result, all the
allocated structures leak.

Save the return value and go into the error path on failure.

The per-object arrays of functions must be freed in the shared
err_free_objs path as well. The cleanup loop in the funcs allocation
failure path is removed instead. Otherwise, it would cause a double
free when the new error path jumps into the shared cleanup.

Fixes: 59adee07b568 ("livepatch/klp-build: Add stub init code for livepatch modules")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/sashiko-outbox-173837@kernel.org/
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 scripts/livepatch/init.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

---

It is based on tip's objtool/urgent branch.

diff --git a/scripts/livepatch/init.c b/scripts/livepatch/init.c
index 16aff8f..a1f6993 100644
--- a/scripts/livepatch/init.c
+++ b/scripts/livepatch/init.c
@@ -50,8 +50,6 @@ static int __init livepatch_mod_init(void)
 		funcs = kzalloc(sizeof(struct klp_func) * (nr_funcs + 1), GFP_KERNEL);
 		if (!funcs) {
 			ret = -ENOMEM;
-			for (int j = 0; j < i; j++)
-				kfree(objs[j].funcs);
 			goto err_free_objs;
 		}
 
@@ -78,9 +76,14 @@ static int __init livepatch_mod_init(void)
 	patch->replace = true;
 #endif
 
-	return klp_enable_patch(patch);
+	ret = klp_enable_patch(patch);
+	if (ret)
+		goto err_free_objs;
+	return 0;
 
 err_free_objs:
+	for (int i = 0; i < nr_objs; i++)
+		kfree(objs[i].funcs);
 	kfree(objs);
 err_free_patch:
 	kfree(patch);
-- 
1.8.3.1