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[embedded] Resolve ptrauth crashes by signing HeapObjects's isa pointers in embedded Swift

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This commit is contained in:
Kuba Mracek
2024-01-22 16:45:07 -08:00
parent 5b05e179f8
commit 2c30b0a0e2
2 changed files with 24 additions and 8 deletions
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13
stdlib/public/core/EmbeddedRuntime.swift
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@@ -19,12 +19,15 @@ public struct ClassMetadata {
// There is no way to express the actual calling convention on the heap desroy
// function (swiftcc with 'self') currently, so let's use UnsafeRawPointer
// and a helper function in C (_swift_runtime_invoke_heap_object_destroy).
// and a helper function in C (_swift_embedded_invoke_heap_object_destroy).
var destroy: UnsafeRawPointer
}
public struct HeapObject {
var metadata: UnsafeMutablePointer<ClassMetadata>
// There is no way to express the custom ptrauth signature on the metadata
// field, so let's use UnsafeRawPointer and a helper function in C instead
// (_swift_embedded_set_heap_object_metadata_pointer).
var metadata: UnsafeRawPointer
// TODO: This is just an initial support for strong refcounting only. We need
// to think about supporting (or banning) weak and/or unowned references.
@@ -82,7 +85,7 @@ public func swift_slowDealloc(_ ptr: UnsafeMutableRawPointer, _ size: Int, _ ali
public func swift_allocObject(metadata: UnsafeMutablePointer<ClassMetadata>, requiredSize: Int, requiredAlignmentMask: Int) -> UnsafeMutablePointer<HeapObject> {
let p = swift_slowAlloc(requiredSize, requiredAlignmentMask)!
let object = p.assumingMemoryBound(to: HeapObject.self)
object.pointee.metadata = metadata
_swift_embedded_set_heap_object_metadata_pointer(object, metadata)
object.pointee.refcount = 1
return object
}
@@ -103,14 +106,14 @@ public func swift_deallocClassInstance(object: UnsafeMutablePointer<HeapObject>,
@_silgen_name("swift_initStaticObject")
public func swift_initStaticObject(metadata: UnsafeMutablePointer<ClassMetadata>, object: UnsafeMutablePointer<HeapObject>) -> UnsafeMutablePointer<HeapObject> {
object.pointee.metadata = metadata
_swift_embedded_set_heap_object_metadata_pointer(object, metadata)
object.pointee.refcount = HeapObject.immortalRefCount
return object
}
@_silgen_name("swift_initStackObject")
public func swift_initStackObject(metadata: UnsafeMutablePointer<ClassMetadata>, object: UnsafeMutablePointer<HeapObject>) -> UnsafeMutablePointer<HeapObject> {
object.pointee.metadata = metadata
_swift_embedded_set_heap_object_metadata_pointer(object, metadata)
object.pointee.refcount = 1 | HeapObject.doNotFreeBit
return object
}