Fix vmmap on remote targets (#2386)

pwndbg/commands/xinfo.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import argparse
+import os
 
 import pwndbg
 import pwndbg.color.memory as M
@@ -59,6 +60,11 @@ def xinfo_mmap_file(page, addr) -> None:
     # to beginning of file in memory and on disk
 
     file_name = page.objfile
+    # Check if the file exists on the local system, as we may be attached to a gdb-server or qemu.
+    # Even so, the file might exist locally, if we are doing `target remote localhost:1234`
+    if not os.path.exists(file_name):
+        return None
+
     objpages = filter(lambda p: p.objfile == file_name, pwndbg.gdblib.vmmap.get())
     first = sorted(objpages, key=lambda p: p.vaddr)[0]
 

pwndbg/gdblib/vmmap.py

@@ -310,7 +310,7 @@ def coredump_maps() -> Tuple[pwndbg.lib.memory.Page, ...]:
     Parses `info proc mappings` and `maintenance info sections`
     and tries to make sense out of the result :)
     """
-    pages = list(info_proc_maps())
+    pages = list(info_proc_maps(parse_flags=False))
 
     started_sections = False
     for line in gdb.execute("maintenance info sections", to_string=True).splitlines():
@@ -392,31 +392,43 @@ def coredump_maps() -> Tuple[pwndbg.lib.memory.Page, ...]:
     return tuple(pages)
 
 
-def parse_info_proc_mappings_line(line: str, parse_flags: bool) -> Optional[pwndbg.lib.memory.Page]:
+def parse_info_proc_mappings_line(
+    line: str, perms_available: bool, parse_flags: bool
+) -> Optional[pwndbg.lib.memory.Page]:
     """
     Parse a line from `info proc mappings` and return a pwndbg.lib.memory.Page
     object if the line is valid.
 
+    Example lines:
+        0x4c3000           0x4c5000     0x2000    0xc2000  rw-p   /root/hello_world/main
+        0x4c5000           0x4cb000     0x6000        0x0  rw-p
+
+    The objfile column might be empty, and the permissions column is only present in GDB versions >= 12.1
+    https://github.com/bminor/binutils-gdb/commit/29ef4c0699e1b46d41ade00ae07a54f979ea21cc
+
     Args:
         line: A line from `info proc mappings`.
 
     Returns:
         A pwndbg.lib.memory.Page object or None.
     """
-
-    # We look for lines like:
-    # ['0x555555555000', '0x555555556000', '0x1000', '0x1000', 'rw-p', '/home/user/a.out']
     try:
+        # Example line with all fields present: ['0x555555555000', '0x555555556000', '0x1000', '0x1000', 'rw-p', '/home/user/a.out']
         split_line = line.split()
 
-        # Permission info is only available in GDB versions >=12.1
-        # https://github.com/bminor/binutils-gdb/commit/29ef4c0699e1b46d41ade00ae07a54f979ea21cc
-        # Assume "rwxp" on older gdb versions
-        if len(split_line) < 6:
-            start_str, _end, size_str, offset_str, objfile = split_line
-            perm = "rwxp"
+        start_str = split_line[0]
+        _end = split_line[1]
+        size_str = split_line[2]
+        offset_str = split_line[3]
+
+        if perms_available:
+            perm = split_line[4]
+            # The objfile column may be empty.
+            objfile = split_line[5] if len(split_line) > 5 else ""
         else:
-            start_str, _end, size_str, offset_str, perm, objfile = split_line
+            perm = "rwxp"
+            objfile = split_line[4] if len(split_line) > 4 else ""
+
         start, size, offset = int(start_str, 16), int(size_str, 16), int(offset_str, 16)
     except (IndexError, ValueError):
         return None
@@ -434,10 +446,25 @@ def parse_info_proc_mappings_line(line: str, parse_flags: bool) -> Optional[pwnd
 
 
 @pwndbg.lib.cache.cache_until("start", "stop")
-def info_proc_maps(parse_flags=False) -> Tuple[pwndbg.lib.memory.Page, ...]:
+def info_proc_maps(parse_flags=True) -> Tuple[pwndbg.lib.memory.Page, ...]:
     """
     Parse the result of info proc mappings.
 
+    Example output:
+
+            Start Addr           End Addr       Size     Offset  Perms  objfile
+              0x400000           0x401000     0x1000        0x0  r--p   /root/hello_world/main
+              0x401000           0x497000    0x96000     0x1000  r-xp   /root/hello_world/main
+              0x497000           0x4be000    0x27000    0x97000  r--p   /root/hello_world/main
+              0x4be000           0x4c3000     0x5000    0xbd000  r--p   /root/hello_world/main
+              0x4c3000           0x4c5000     0x2000    0xc2000  rw-p   /root/hello_world/main
+              0x4c5000           0x4cb000     0x6000        0x0  rw-p
+              0x4cb000           0x4ed000    0x22000        0x0  rw-p   [heap]
+        0x7ffff7ff9000     0x7ffff7ffd000     0x4000        0x0  r--p   [vvar]
+        0x7ffff7ffd000     0x7ffff7fff000     0x2000        0x0  r-xp   [vdso]
+        0x7ffffffde000     0x7ffffffff000    0x21000        0x0  rw-p   [stack]
+    0xffffffffff600000 0xffffffffff601000     0x1000        0x0  --xp   [vsyscall]
+
     Note: this may return no pages due to a bug/behavior of GDB.
     See https://sourceware.org/bugzilla/show_bug.cgi?id=31207
     for more information.
@@ -453,9 +480,12 @@ def info_proc_maps(parse_flags=False) -> Tuple[pwndbg.lib.memory.Page, ...]:
         # On qemu user emulation, we may get: gdb.error: Not supported on this target.
         info_proc_mappings = []
 
+    # See if "Perms" is in the header line
+    perms_available = "Perms" in info_proc_mappings[3]
+
     pages: List[pwndbg.lib.memory.Page] = []
     for line in info_proc_mappings:
-        page = parse_info_proc_mappings_line(line, parse_flags)
+        page = parse_info_proc_mappings_line(line, perms_available, parse_flags)
         if page is not None:
             pages.append(page)