Demo enhancement and RCU correction

.github/workflows/ci.yml

@@ -20,7 +20,9 @@ jobs:
     - name: Build the exploit
       run: make
     - name: Install QEMU
-      run: sudo apt-get install -y qemu-system-x86-64
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y qemu-system-x86-64
     - name: Run the exploit
       id: test
       continue-on-error: true

README.md

@@ -5,6 +5,8 @@
 
  [ci]: https://github.com/lrh2000/StackRot/actions
 
+![Demo](pic/demo.svg)
+
 A flaw was found in the handling of stack expansion in the Linux kernel 6.1
 through 6.4, aka "Stack Rot". The maple tree, responsible for managing virtual
 memory areas, can undergo node replacement without properly acquiring the MM
@@ -358,12 +360,11 @@ solutions are as follows:
     period will not end.
  4. The iteration task is deliberately prolonged, allowing the RCU grace period
     to expire. This is the chosen solution. If the current RCU grace period
-    surpasses RCU_TASK_IPI_DELAY (defaulting to 0.5 seconds), inter-processor
-    interrupts (IPIs) are dispatched to all CPUs to verify that they are not in
-    RCU critical sections. In the case of VMA iteration, the answer is
-    negative, signifying that the RCU grace period concludes and the maple node
-    is freed, effectively converting UAFBR into a genuine use-after-free (UAF)
-    scenario.
+    surpasses `jiffies_till_first_fqs` (defaulting to several jiffies), an
+    inter-processor interrupt (IPI) will be dispatched to the victim CPU and
+    trigger voluntary preemption. In the case of VMA iteration, the voluntary
+    preemption can make the RCU grace period conclude and free the maple node,
+    effectively converting UAFBR into a genuine use-after-free (UAF) scenario.
 
 One significant observation is that during VMA iteration for
 `/proc/[pid]/maps`, it generates the entire file path for file-mapped memory