Fix unsafe access to CodeCache (#175)

jbachorik · apangin · web-flow · commit 3bf096458ff9 · 2025-02-04T15:39:14.000+01:00
Co-authored-by: Andrei Pangin &lt;noreply@pangin.pro&gt;
diff --git a/ddprof-lib/src/main/cpp/stackWalker.cpp b/ddprof-lib/src/main/cpp/stackWalker.cpp
@@ -158,7 +158,8 @@ int StackWalker::walkDwarf(void *ucontext, const void **callchain,
     }
     if (CodeHeap::contains(pc) && !(depth == 0 && frame.unwindAtomicStub(pc))) {
       const void* page_start = (const void*)((uintptr_t)pc & ~0xfffUL);
-      frame.adjustSP(page_start, pc, sp);
+      // Don't dereference pc as it may point to unreadable memory
+      // frame.adjustSP(page_start, pc, sp);
       java_ctx->set(pc, sp, fp);
       break;
     }

Original file line number	Diff line number	Diff line change
`@@ -158,7 +158,8 @@ int StackWalker::walkDwarf(void ucontext, const void *callchain,`
`158`	`158`	`}`
`159`	`159`	`if (CodeHeap::contains(pc) && !(depth == 0 && frame.unwindAtomicStub(pc))) {`
`160`	`160`	`const void* page_start = (const void*)((uintptr_t)pc & ~0xfffUL);`
`161`		`- frame.adjustSP(page_start, pc, sp);`
	`161`	`+ // Don't dereference pc as it may point to unreadable memory`
	`162`	`+ // frame.adjustSP(page_start, pc, sp);`
`162`	`163`	`java_ctx->set(pc, sp, fp);`
`163`	`164`	`break;`
`164`	`165`	`}`