From: Artem Savkov asavkov@redhat.com
commit d9815bff6b379ff46981bea9dfeb146081eab314 upstream.
It appears that ip ranges can overlap so. In that case lookup_rec() returns whatever results it got last even if it found nothing in last searched page.
This breaks an obscure livepatch late module patching usecase: - load livepatch - load the patched module - unload livepatch - try to load livepatch again
To fix this return from lookup_rec() as soon as it found the record containing searched-for ip. This used to be this way prior lookup_rec() introduction.
Link: http://lkml.kernel.org/r/20200306174317.21699-1-asavkov@redhat.com
Cc: stable@vger.kernel.org Fixes: 7e16f581a817 ("ftrace: Separate out functionality from ftrace_location_range()") Signed-off-by: Artem Savkov asavkov@redhat.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/trace/ftrace.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1552,6 +1552,8 @@ static struct dyn_ftrace *lookup_rec(uns rec = bsearch(&key, pg->records, pg->index, sizeof(struct dyn_ftrace), ftrace_cmp_recs); + if (rec) + break; } return rec; }