drgn.helpers.common.memory: fix identify_address vmap identification …

…with CONFIG_VMAP_STACK=n In the uncached case, the task variable is supposed to be the task that matched the vm area. But, if we detect that CONFIG_VMAP_STACK is disabled, we break without clearing the task variable. Fix that, and also make sure to test both the cached and uncached cases. Closes #414. Fixes: 69bd07d ("drgn.helpers.common.memory: add optional cache to identify_address()") Reported-by: Sourabh Jain <[email protected]> Signed-off-by: Omar Sandoval <[email protected]>
osandov · Jul 25, 2024 · 9ad29fd · 9ad29fd
1 parent 1832240
commit 9ad29fd
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Showing 2 changed files with 18 additions and 9 deletions.
diff --git a/drgn/helpers/common/memory.py b/drgn/helpers/common/memory.py
@@ -54,6 +54,7 @@ def _identify_kernel_vmap(
                     break
             except AttributeError:
                 # CONFIG_VMAP_STACK must be disabled.
+                task = None
                 break
             except FaultError:
                 continue

diff --git a/tests/linux_kernel/helpers/test_common.py b/tests/linux_kernel/helpers/test_common.py
@@ -52,20 +52,28 @@ def test_identify_slab_cache(self):
 
     @skip_unless_have_test_kmod
     def test_identify_vmap(self):
-        self.assertTrue(
-            identify_address(self.prog["drgn_test_vmalloc_va"]).startswith("vmap: 0x")
-        )
+        for cache in (None, {}):
+            with self.subTest("uncached" if cache is None else "cached"):
+                self.assertTrue(
+                    identify_address(
+                        self.prog["drgn_test_vmalloc_va"], cache=cache
+                    ).startswith("vmap: 0x")
+                )
 
     @skip_unless_have_test_kmod
     def test_identify_vmap_stack(self):
         if not self.prog["drgn_test_vmap_stack_enabled"]:
             self.skipTest("kernel does not use vmap stacks (CONFIG_VMAP_STACK)")
-        self.assertEqual(
-            identify_address(
-                self.prog, self.prog["drgn_test_kthread"].stack.value_() + 1234
-            ),
-            f"vmap stack: {self.prog['drgn_test_kthread'].pid.value_()} (drgn_test_kthre) +0x4d2",
-        )
+        for cache in (None, {}):
+            with self.subTest("uncached" if cache is None else "cached"):
+                self.assertEqual(
+                    identify_address(
+                        self.prog,
+                        self.prog["drgn_test_kthread"].stack.value_() + 1234,
+                        cache=cache,
+                    ),
+                    f"vmap stack: {self.prog['drgn_test_kthread'].pid.value_()} (drgn_test_kthre) +0x4d2",
+                )
 
     @skip_unless_have_full_mm_support
     @skip_unless_have_test_kmod