FAILED: patch "[PATCH] tracing: Verify event formats that have "%*p.."" failed to apply to 6.1-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x ea8d7647f9ddf1f81e2027ed305299797299aa03
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025040812-pulse-unsaid-621c@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ea8d7647f9ddf1f81e2027ed305299797299aa03 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt@goodmis.org>
Date: Thu, 27 Mar 2025 19:53:11 -0400
Subject: [PATCH] tracing: Verify event formats that have "%*p.."

The trace event verifier checks the formats of trace events to make sure
that they do not point at memory that is not in the trace event itself or
in data that will never be freed. If an event references data that was
allocated when the event triggered and that same data is freed before the
event is read, then the kernel can crash by reading freed memory.

The verifier runs at boot up (or module load) and scans the print formats
of the events and checks their arguments to make sure that dereferenced
pointers are safe. If the format uses "%*p.." the verifier will ignore it,
and that could be dangerous. Cover this case as well.

Also add to the sample code a use case of "%*pbl".

Link: https://lore.kernel.org/all/bcba4d76-2c3f-4d11-baf0-02905db953dd@oracle.com/

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: 5013f454a352c ("tracing: Add check of trace event print fmts for dereferencing pointers")
Link: https://lore.kernel.org/20250327195311.2d89ec66@gandalf.local.home
Reported-by: Libo Chen <libo.chen@oracle.com>
Reviewed-by: Libo Chen <libo.chen@oracle.com>
Tested-by: Libo Chen <libo.chen@oracle.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 8638b7f7ff85..069e92856bda 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -470,6 +470,7 @@ static void test_event_printk(struct trace_event_call *call)
 			case '%':
 				continue;
 			case 'p':
+ do_pointer:
 				/* Find dereferencing fields */
 				switch (fmt[i + 1]) {
 				case 'B': case 'R': case 'r':
@@ -498,6 +499,12 @@ static void test_event_printk(struct trace_event_call *call)
 						continue;
 					if (fmt[i + j] == '*') {
 						star = true;
+						/* Handle %*pbl case */
+						if (!j && fmt[i + 1] == 'p') {
+							arg++;
+							i++;
+							goto do_pointer;
+						}
 						continue;
 					}
 					if ((fmt[i + j] == 's')) {
diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h
index 999f78d380ae..1a05fc153353 100644
--- a/samples/trace_events/trace-events-sample.h
+++ b/samples/trace_events/trace-events-sample.h
@@ -319,7 +319,8 @@ TRACE_EVENT(foo_bar,
 		__assign_cpumask(cpum, cpumask_bits(mask));
 	),
 
-	TP_printk("foo %s %d %s %s %s %s %s %s (%s) (%s) %s", __entry->foo, __entry->bar,
+	TP_printk("foo %s %d %s %s %s %s %s %s (%s) (%s) %s [%d] %*pbl",
+		  __entry->foo, __entry->bar,
 
 /*
  * Notice here the use of some helper functions. This includes:
@@ -370,7 +371,10 @@ TRACE_EVENT(foo_bar,
 
 		  __get_str(str), __get_str(lstr),
 		  __get_bitmask(cpus), __get_cpumask(cpum),
-		  __get_str(vstr))
+		  __get_str(vstr),
+		  __get_dynamic_array_len(cpus),
+		  __get_dynamic_array_len(cpus),
+		  __get_dynamic_array(cpus))
 );
 
 /*