kprobes: Prohibit probing on RCU debug routine

BugLink: https://bugs.launchpad.net/bugs/1838116
[ Upstream commit a39f15b9644fac3f950f522c39e667c3af25c588 ]

Since kprobe itself depends on RCU, probing on RCU debug
routine can cause recursive breakpoint bugs.

Prohibit probing on RCU debug routines.

int3
 ->do_int3()
   ->ist_enter()
     ->RCU_LOCKDEP_WARN()
       ->debug_lockdep_rcu_enabled() -> int3

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrea Righi <righi.andrea@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/154998807741.31052.11229157537816341591.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 68fa19a5e7bd9a63dcf1e0d3f4b1e59b9113000b..0846d4069f4e4de4570724ab2388b4f74f79540c 100644 (file)
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -52,6 +52,7 @@
 #include <linux/tick.h>
 #include <linux/rcupdate_wait.h>
 #include <linux/sched/isolation.h>
+#include <linux/kprobes.h>
 
 #define CREATE_TRACE_POINTS
 
@@ -301,6 +302,7 @@ int notrace debug_lockdep_rcu_enabled(void)
               current->lockdep_recursion == 0;
 }
 EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
+NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled);
 
 /**
  * rcu_read_lock_held() - might we be in RCU read-side critical section?