From 52248c2a93d8e7f281511728f235b852882cfc6c Mon Sep 17 00:00:00 2001
From: Pankaj Singh <pankajsingh@meta.com>
Date: Mon, 28 Oct 2024 12:05:50 -0700
Subject: [PATCH] add validity check AlignedTableTightAlloc clear method
 (#3997)

Summary:

Avoid null pointer error by checking that `numel > 0`.
It's equivalent of checking`ptr != null` but keeping numel check for consistency.

Bug reported in: https://github.com/facebookresearch/faiss/issues/3994

Reviewed By: mnorris11

Differential Revision: D65073502
---
 faiss/utils/AlignedTable.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/faiss/utils/AlignedTable.h b/faiss/utils/AlignedTable.h
index f570797a01..216dae01fc 100644
--- a/faiss/utils/AlignedTable.h
+++ b/faiss/utils/AlignedTable.h
@@ -63,7 +63,9 @@ struct AlignedTableTightAlloc {
     }
 
     void clear() {
-        memset(ptr, 0, nbytes());
+        if (numel > 0) {
+            memset(ptr, 0, nbytes());
+        }
     }
     size_t size() const {
         return numel;