From 4b750b573c5b3ee10e33c1573eaa94a9dad62f19 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Thu, 5 Nov 2020 21:32:42 -0500 Subject: livepatch: Trigger WARNING if livepatch function fails due to recursion If for some reason a function is called that triggers the recursion detection of live patching, trigger a warning. By not executing the live patch code, it is possible that the old unpatched function will be called placing the system into an unknown state. Link: https://lore.kernel.org/r/20201029145709.GD16774@alley Link: https://lkml.kernel.org/r/20201106023547.312639435@goodmis.org Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Joe Lawrence Cc: live-patching@vger.kernel.org Suggested-by: Miroslav Benes Reviewed-by: Petr Mladek Acked-by: Miroslav Benes Signed-off-by: Steven Rostedt (VMware) --- kernel/livepatch/patch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c index 6c0164d24bbd..15480bf3ce88 100644 --- a/kernel/livepatch/patch.c +++ b/kernel/livepatch/patch.c @@ -50,7 +50,7 @@ static void notrace klp_ftrace_handler(unsigned long ip, ops = container_of(fops, struct klp_ops, fops); bit = ftrace_test_recursion_trylock(); - if (bit < 0) + if (WARN_ON_ONCE(bit < 0)) return; /* * A variant of synchronize_rcu() is used to allow patching functions -- cgit v1.2.3