From: "Steven Rostedt (VMware)" <[email protected]> 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 Cc: Josh Poimboeuf <[email protected]> Cc: Jiri Kosina <[email protected]> Cc: Miroslav Benes <[email protected]> Cc: Joe Lawrence <[email protected]> Cc: [email protected] Suggested-by: Petr Mladek <[email protected]> Signed-off-by: Steven Rostedt (VMware) <[email protected]> --- 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 -- 2.28.0
