Merge tag 'trace-v5.12-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fix from Steven Rostedt:
 "Fix tp_printk command line and trace events

  Masami added a wrapper to be able to unhash trace event pointers as
  they are only read by root anyway, and they can also be extracted by
  the raw trace data buffers. But this wrapper utilized the iterator to
  have a temporary buffer to manipulate the text with.

  tp_printk is a kernel command line option that will send the trace
  output of a trace event to the console on boot up (useful when the
  system crashes before finishing the boot). But the code used the same
  wrapper that Masami added, and its iterator did not have a buffer, and
  this caused the system to crash.

  Have the wrapper just print the trace event normally if the iterator
  has no temporary buffer"

* tag 'trace-v5.12-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix checking event hash pointer logic when tp_printk is enabled

1 files changed, 7 insertions, 3 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5c777627212f..c0c9aa5cd8e2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3545,7 +3545,11 @@ static char *trace_iter_expand_format(struct trace_iterator *iter)
 {
 	char *tmp;
 
-	if (iter->fmt == static_fmt_buf)
+	/*
+	 * iter->tr is NULL when used with tp_printk, which makes
+	 * this get called where it is not safe to call krealloc().
+	 */
+	if (!iter->tr || iter->fmt == static_fmt_buf)
 		return NULL;
 
 	tmp = krealloc(iter->fmt, iter->fmt_size + STATIC_FMT_BUF_SIZE,
@@ -3566,7 +3570,7 @@ const char *trace_event_format(struct trace_iterator *iter, const char *fmt)
 	if (WARN_ON_ONCE(!fmt))
 		return fmt;
 
-	if (iter->tr->trace_flags & TRACE_ITER_HASH_PTR)
+	if (!iter->tr || iter->tr->trace_flags & TRACE_ITER_HASH_PTR)
 		return fmt;
 
 	p = fmt;
@@ -9692,7 +9696,7 @@ void __init early_trace_init(void)
 {
 	if (tracepoint_printk) {
 		tracepoint_print_iter =
-			kmalloc(sizeof(*tracepoint_print_iter), GFP_KERNEL);
+			kzalloc(sizeof(*tracepoint_print_iter), GFP_KERNEL);
 		if (MEM_FAIL(!tracepoint_print_iter,
 			     "Failed to allocate trace iterator\n"))
 			tracepoint_printk = 0;