From 38d16a82eb4a8b0e393b51cc3e9144dc7b413fd1 Mon Sep 17 00:00:00 2001
From: Vitah Lin <vitahlin@gmail.com>
Date: Thu, 28 Aug 2025 21:17:55 +0800
Subject: [PATCH] Fix missing prev update in hnsw_cursor_free causing unlink
 failure (#14050)

This PR fixes a bug in the `hnsw_cursor_free` function where the prev
pointer was never updated during cursor list traversal. As a result, if
the cursor being freed was not the head of the list, it would not be
correctly unlinked, potentially causing memory leaks or corruption of
the cursor list.

Note that since `hnsw_cursor_free()` is never used for now, this PR does
not actually fix any bug.
---
 modules/vector-sets/hnsw.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/modules/vector-sets/hnsw.c b/modules/vector-sets/hnsw.c
index cae43e305..9895522f8 100644
--- a/modules/vector-sets/hnsw.c
+++ b/modules/vector-sets/hnsw.c
@@ -2489,6 +2489,7 @@ void hnsw_cursor_free(hnswCursor *cursor) {
             hfree(cursor);
             break;
         }
+        prev = x;
         x = x->next;
     }
     pthread_rwlock_unlock(&cursor->index->global_lock);