Paul Gofman : ntdll: Avoid integer overflow in block_get_subheap().

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 27c4c64c367f47fe7914c5c87596e6cf3501dbd6
URL:    https://gitlab.winehq.org/wine/wine/-/commit/27c4c64c367f47fe7914c5c87596e6c...

Author: Paul Gofman 
Date:   Fri Apr 21 19:19:20 2023 -0600

ntdll: Avoid integer overflow in block_get_subheap().

---

dlls/ntdll/heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/ntdll/heap.c b/dlls/ntdll/heap.c
index d8dab867ff5..ef1a9c3f3b1 100644
--- a/dlls/ntdll/heap.c
+++ b/dlls/ntdll/heap.c
@@ -359,7 +359,7 @@ static inline void block_set_type( struct block *block, UINT type )
 static inline SUBHEAP *block_get_subheap( const struct heap *heap, const struct block *block )
 {
     char *offset = ROUND_ADDR( block, REGION_ALIGN - 1 );
-    void *base = offset - block->base_offset * REGION_ALIGN;
+    void *base = offset - (SIZE_T)block->base_offset * REGION_ALIGN;
     if (base != (void *)heap) return base;
     else return (SUBHEAP *)&heap->subheap;
 }