abd_return_buf() should call zfs_refcount_remove_many() early

Calling zfs_refcount_remove_many() after freeing memory means we pass a reference to freed memory as the holder. This is not believed to be able to cause a problem, but there is a bit of a tradition of fixing these issues when they appear so that they do not obscure more serious issues in static analyzer output, so we fix this one too. Clang's static analyzer found this with the help of CodeChecker's CTU analysis. Signed-off-by: Richard Yao <[email protected]>
openzfs · Oct 17, 2022 · 587f8b1 · 587f8b1
1 parent 61417dd
commit 587f8b1
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/module/zfs/abd.c b/module/zfs/abd.c
@@ -667,15 +667,15 @@ abd_return_buf(abd_t *abd, void *buf, size_t n)
 {
 	abd_verify(abd);
 	ASSERT3U(abd->abd_size, >=, n);
+#ifdef ZFS_DEBUG
+	(void) zfs_refcount_remove_many(&abd->abd_children, n, buf);
+#endif
 	if (abd_is_linear(abd)) {
 		ASSERT3P(buf, ==, abd_to_buf(abd));
 	} else {
 		ASSERT0(abd_cmp_buf(abd, buf, n));
 		zio_buf_free(buf, n);
 	}
-#ifdef ZFS_DEBUG
-	(void) zfs_refcount_remove_many(&abd->abd_children, n, buf);
-#endif
 }
 
 void