Add config to override libc version.

docs/commands/heap.md

@@ -30,6 +30,14 @@ gef➤ gef config gef.bruteforce_main_arena True
 Note that this might take a few seconds to complete. If GEF does find the symbol you can then
 calculate the offset to the libc base address and save it in the config.
 
+Sometimes, the dump might not contain proper info to help GEF find the libc version, which results in
+failure to parse the arena information. In this case, you can try to provide GEF a specific libc
+version to use with the following command:
+
+```text
+gef➤ gef config gef.libc_version 2.31
+```
+
 ### `heap chunks` command
 
 Displays all the chunks from the `heap` section of the current arena.

gef.py

@@ -9587,6 +9587,7 @@ def __init__(self) -> None:
         gef.config["gef.show_deprecation_warnings"] = GefSetting(True, bool, "Toggle the display of the `deprecated` warnings")
         gef.config["gef.buffer"] = GefSetting(True, bool, "Internally buffer command output until completion")
         gef.config["gef.bruteforce_main_arena"] = GefSetting(False, bool, "Allow bruteforcing main_arena symbol if everything else fails")
+        gef.config["gef.libc_version"] = GefSetting("", str, "Specify libc version when auto-detection fails")
         gef.config["gef.main_arena_offset"] = GefSetting("", str, "Offset from libc base address to main_arena symbol (int or hex). Set to empty string to disable.")
 
         self.commands : Dict[str, GenericCommand] = collections.OrderedDict()
@@ -11166,8 +11167,14 @@ def __str__(self) -> str:
     def version(self) -> Optional[Tuple[int, int]]:
         if not is_alive():
             return None
+
         if not self._version:
             self._version = GefLibcManager.find_libc_version()
+
+        # Whenever auto-detection fails, we use the user-provided version.
+        if self._version == (0, 0) and gef.config["gef.libc_version"] != "":
+            return tuple([int(v) for v in gef.config["gef.libc_version"].split(".")])
+
         return self._version
 
     @staticmethod

tests/config/__init__.py

@@ -2,7 +2,7 @@
 Test GEF configuration parameters.
 """
 
-from tests.utils import gdb_run_cmd
+from tests.utils import gdb_run_cmd, gdb_start_silent_cmd
 from tests.utils import GefUnitTestGeneric
 
 
@@ -49,3 +49,23 @@ def test_config_type_validator(self):
         res = gdb_run_cmd("gef config gef.debug 0")
         self.assertNoException(res)
         self.assertNotIn("[!]", res)
+
+    def test_config_libc_version(self):
+        """Check setting libc version."""
+        res = gdb_run_cmd("gef config gef.libc_version")
+        self.assertNoException(res)
+        self.assertNotIn("[!]", res)
+
+        res = gdb_run_cmd("gef config gef.libc_version", before=["gef config gef.libc_version 2.31"])
+        self.assertNoException(res)
+        self.assertNotIn("[!]", res)
+        self.assertIn('gef.libc_version (str) = "2.31"', res)
+
+        res = gdb_run_cmd("gef config gef.libc_version", before=["gef config gef.libc_version 2.31", "gef config gef.libc_version ''"])
+        self.assertNoException(res)
+        self.assertNotIn("[!]", res)
+        self.assertIn('gef.libc_version (str) = ""', res)
+
+        res = gdb_start_silent_cmd("python print(gef.libc.version)", before=["gef config gef.libc_version 2.31"])
+        self.assertNoException(res)
+        self.assertNotIn("[!]", res)