Rémi Bernon : ntdll: Avoid shrinking large heap block to small block.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 63fb16338c4017a80cbe49d0f5f232babb1a5f1a
URL:    https://gitlab.winehq.org/wine/wine/-/commit/63fb16338c4017a80cbe49d0f5f232b...

Author: Rémi Bernon 
Date:   Mon Feb 20 14:20:20 2023 +0100

ntdll: Avoid shrinking large heap block to small block.

Even though this is a waste of memory it seems to trip on some UAF with
some games.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=54475

---

dlls/ntdll/heap.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/dlls/ntdll/heap.c b/dlls/ntdll/heap.c
index afe38eddaa8..6688fab9690 100644
--- a/dlls/ntdll/heap.c
+++ b/dlls/ntdll/heap.c
@@ -2092,7 +2092,6 @@ static NTSTATUS heap_resize_large( struct heap *heap, ULONG flags, struct block
     SIZE_T old_block_size = large->block_size;
     *old_size = large->data_size;

-    if (block_size < HEAP_MIN_LARGE_BLOCK_SIZE / 4) return STATUS_NO_MEMORY;  /* shrinking large block to small block */
     if (old_block_size < block_size) return STATUS_NO_MEMORY;

/* FIXME: we could remap zero-pages instead */