mm/damon/sysfs: fix param_ctx leak on damon_sysfs_new_test_ctx() failure

Patch series "mm/damon/sysfs: fix memory leak and NULL dereference
issues", v4.

DAMON_SYSFS can leak memory under allocation failure, and do NULL pointer
dereference when a privileged user make wrong sequences of control.  Fix
those.


This patch (of 3):

When damon_sysfs_new_test_ctx() fails in damon_sysfs_commit_input(),
param_ctx is leaked because the early return skips the cleanup at the out
label.  Destroy param_ctx before returning.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: f0c5118 ("mm/damon/sysfs: catch commit test ctx alloc failure")
Signed-off-by: Josh Law <[email protected]>
Reviewed-by: SeongJae Park <[email protected]>
Signed-off-by: SeongJae Park <[email protected]>
Cc: <[email protected]>	[6.18+]
Signed-off-by: Andrew Morton <[email protected]>

Author: techyguyperplexable

mm/damon/sysfs.c

@@ -1524,8 +1524,10 @@ static int damon_sysfs_commit_input(void *data)
 	if (IS_ERR(param_ctx))
 		return PTR_ERR(param_ctx);
 	test_ctx = damon_sysfs_new_test_ctx(kdamond->damon_ctx);
-	if (!test_ctx)
+	if (!test_ctx) {
+		damon_destroy_ctx(param_ctx);
 		return -ENOMEM;
+	}
 	err = damon_commit_ctx(test_ctx, param_ctx);
 	if (err)
 		goto out;