ntdll: Fix handling of back pointer in heap_set_debug_flags.

Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>

ntdll: Fix handling of back pointer in heap_set_debug_flags.
75f2af28 · Rémi Bernon · Alexandre Julliard · e2412025 · 75f2af28
Commit 75f2af28 authored May 30, 2022 by Rémi Bernon Committed by Alexandre Julliard May 31, 2022
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heap.c dlls/ntdll/heap.c +3 -2

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--- a/dlls/ntdll/heap.c
+++ b/dlls/ntdll/heap.c
@@ -1337,8 +1337,9 @@ static void heap_set_debug_flags( HANDLE handle )
                if (block_get_flags( block ) & BLOCK_FLAG_FREE)
                {
                    char *data = (char *)block + block_get_overhead( block ), *end = (char *)block + block_get_size( block );
-                    if (end >= commit_end) mark_block_free( data, commit_end - data, flags );
-                    else mark_block_free( data, end - sizeof(struct block *) - data, flags );
+                    if (next_block( subheap, block )) end -= sizeof(struct block *);
+                    if (end > commit_end) mark_block_free( data, commit_end - data, flags );
+                    else mark_block_free( data, end - data, flags );
                }
                else
                {