ggml/gguf : prevent integer overflows (#19856)

* gguf : prevent integer overflow for ggml_context mem size

* ggml : fix int overflows in ggml_new_object()

* gguf : prevent string exhaustion

* gguf : prevent array elements exhaustion

* ggml : fix negative tensor type oob

* py : assert that alignment is non-zero power of 2

* ggml : check int overflow in ggml_new_tensor_impl and ggml_new_object

* gguf-py : error on duplicate keys when reading

* py : restore tensor_fields

* enforce proper alignment in add_custom_alignment

* gguf : better name

* gguf : fix ctx size for no_alloc == true

* gguf : minor print fix

* ggml : print values when overflow

* ggml : remove deprecated ggml_type_sizef()

* ggml : relax ggml_type asserts to debug-only

* gguf : add mem_size overflow test

* gguf : add file size check for arrays

* ggml : relax asseerts for ggml_get_type_traits()

* flake8 fix

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

gguf-py/gguf/gguf_writer.py

@@ -501,6 +501,8 @@ class GGUFWriter:
         self.add_uint32(Keys.General.QUANTIZATION_VERSION, quantization_version)
 
     def add_custom_alignment(self, alignment: int) -> None:
+        if alignment <= 0 or (alignment & (alignment - 1)) != 0:
+            raise ValueError('Invalid alignment: must be a non-zero power of two')
         self.data_alignment = alignment
         self.add_uint32(Keys.General.ALIGNMENT, alignment)