[wasm] Be more cautious about page zeroing (#106080)

Should fix #106007
dotnet · Aug 8, 2024 · 68511fd · 68511fd
1 parent 679a284
commit 68511fd
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/src/mono/mono/utils/lock-free-alloc.c b/src/mono/mono/utils/lock-free-alloc.c
@@ -125,7 +125,7 @@ static unsigned long
 prot_flags_for_activate (int activate)
 {
 	unsigned long prot_flags = activate? MONO_MMAP_READ|MONO_MMAP_WRITE: MONO_MMAP_NONE;
-	return prot_flags | MONO_MMAP_PRIVATE | MONO_MMAP_ANON | MONO_MMAP_NOZERO;
+	return prot_flags | MONO_MMAP_PRIVATE | MONO_MMAP_ANON;
 }
 
 static gpointer
@@ -138,13 +138,15 @@ alloc_sb (Descriptor *desc)
 	if (pagesize == -1)
 		pagesize = mono_pagesize ();
 
+	// NOTE: Allocated memory is not guaranteed to be zeroed
 	sb_header = desc->block_size == pagesize ?
-		mono_valloc (NULL, desc->block_size, prot_flags_for_activate (TRUE), desc->heap->account_type) :
-		mono_valloc_aligned (desc->block_size, desc->block_size, prot_flags_for_activate (TRUE), desc->heap->account_type);
+		mono_valloc (NULL, desc->block_size, prot_flags_for_activate (TRUE) | MONO_MMAP_NOZERO, desc->heap->account_type) :
+		mono_valloc_aligned (desc->block_size, desc->block_size, prot_flags_for_activate (TRUE) | MONO_MMAP_NOZERO, desc->heap->account_type);
 
 	g_assertf (sb_header, "Failed to allocate memory for the lock free allocator");
 	g_assert (sb_header == sb_header_for_addr (sb_header, desc->block_size));
 
+	// Initializes the header fully
 	*(Descriptor**)sb_header = desc;
 	//g_print ("sb %p for %p\n", sb_header, desc);