tracing: Add a helper function to handle the dereference arg in verifier

Add a helper function called handle_dereference_arg() to replace the logic
that is identical in two locations of test_event_printk().

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250507191703.5dd8a61d@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index fe0ea14d809e845028b7b894ada17f16536ce266..120531268abff8cb779fc406545e050bbe672e2d 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -400,6 +400,20 @@ static bool process_string(const char *fmt, int len, struct trace_event_call *ca
        return true;
 }
 
+static void handle_dereference_arg(const char *arg_str, u64 string_flags, int len,
+                                  u64 *dereference_flags, int arg,
+                                  struct trace_event_call *call)
+{
+       if (string_flags & (1ULL << arg)) {
+               if (process_string(arg_str, len, call))
+                       *dereference_flags &= ~(1ULL << arg);
+       } else if (process_pointer(arg_str, len, call))
+               *dereference_flags &= ~(1ULL << arg);
+       else
+               pr_warn("TRACE EVENT ERROR: Bad dereference argument: '%.*s'\n",
+                       len, arg_str);
+}
+
 /*
  * Examine the print fmt of the event looking for unsafe dereference
  * pointers using %p* that could be recorded in the trace event and
@@ -563,11 +577,9 @@ static void test_event_printk(struct trace_event_call *call)
                        }
 
                        if (dereference_flags & (1ULL << arg)) {
-                               if (string_flags & (1ULL << arg)) {
-                                       if (process_string(fmt + start_arg, e - start_arg, call))
-                                               dereference_flags &= ~(1ULL << arg);
-                               } else if (process_pointer(fmt + start_arg, e - start_arg, call))
-                                       dereference_flags &= ~(1ULL << arg);
+                               handle_dereference_arg(fmt + start_arg, string_flags,
+                                                      e - start_arg,
+                                                      &dereference_flags, arg, call);
                        }
 
                        start_arg = i;
@@ -578,11 +590,9 @@ static void test_event_printk(struct trace_event_call *call)
        }
 
        if (dereference_flags & (1ULL << arg)) {
-               if (string_flags & (1ULL << arg)) {
-                       if (process_string(fmt + start_arg, i - start_arg, call))
-                               dereference_flags &= ~(1ULL << arg);
-               } else if (process_pointer(fmt + start_arg, i - start_arg, call))
-                       dereference_flags &= ~(1ULL << arg);
+               handle_dereference_arg(fmt + start_arg, string_flags,
+                                      i - start_arg,
+                                      &dereference_flags, arg, call);
        }
 
        /*