handle `kbase == None` (#3393)

* handle `kbase == None`

* handle more none cases

pwndbg/aglib/kernel/kallsyms.py

@@ -44,6 +44,9 @@ class Kallsyms:
     def __init__(self):
         self.kallsyms: List[Tuple[str, str, int]] = []
         self.kbase = pwndbg.aglib.kernel.kbase()
+        if self.kbase is None:
+            print(M.warn("could not find kbase, kernel has not finished initialization?"))
+            return
 
         mapping = pwndbg.aglib.kernel.first_kernel_ro_page()
         assert mapping is not None, "kernel memory mappings are missing"

pwndbg/aglib/kernel/paging.py

@@ -91,6 +91,8 @@ class ArchPagingInfo:
         raise NotImplementedError()
 
     def kbase_helper(self, address):
+        if address is None:
+            return None
         for mapping in kernel_vmmap_pages():
             # should be page aligned -- either from pt-dump or info mem
 
@@ -220,7 +222,10 @@ class x86_64PagingInfo(ArchPagingInfo):
     @property
     @pwndbg.lib.cache.cache_until("stop")
     def kbase(self):
-        return self.kbase_helper(pwndbg.aglib.kernel.get_idt_entries()[0].offset)
+        idt_entries = pwndbg.aglib.kernel.get_idt_entries()
+        if len(idt_entries) == 0:
+            return None
+        return self.kbase_helper(idt_entries[0].offset)
 
     @property
     def page_shift(self) -> int:
@@ -290,10 +295,10 @@ class x86_64PagingInfo(ArchPagingInfo):
 
     def handle_kernel_pages(self, pages):
         kernel_idx = None
+        kbase = self.kbase
         for i, page in enumerate(pages):
-            if kernel_idx is None and self.kbase in page:
+            if kernel_idx is None and kbase is not None and kbase in page:
                 kernel_idx = i
-        kbase = self.kbase
         if kernel_idx is None:
             return
         has_loadable_driver = False
@@ -384,6 +389,8 @@ class Aarch64PagingInfo(ArchPagingInfo):
     @property
     @pwndbg.lib.cache.cache_until("stop")
     def module_start(self):
+        if self.kbase is None:
+            return None
         res = None
         for page in kernel_vmmap_pages()[::-1]:
             if page.start >= self.kbase:
@@ -534,6 +541,8 @@ class Aarch64PagingInfo(ArchPagingInfo):
                 if value == 0xFFFFFFFFFFFFFFFF:
                     break
             return tuple(sections)
+        vmalloc_end = None
+        if self.vmemmap and self.pci and self.fixmap:
             vmalloc_end = min(self.vmemmap, self.pci, self.fixmap)
         return (
             (self.USERLAND, 0),
@@ -565,6 +574,8 @@ class Aarch64PagingInfo(ArchPagingInfo):
         return " ".join(name.strip().split()[:-1])
 
     def handle_kernel_pages(self, pages):
+        if self.kbase is None:
+            return
         for i in range(len(pages)):
             page = pages[i]
             if page.start > self.kbase + self.ksize: