Patch "tracing/synthetic: Allocate one additional element for size" has been added to the 6.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    tracing/synthetic: Allocate one additional element for size

to the 6.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tracing-synthetic-allocate-one-additional-element-fo.patch
and it can be found in the queue-6.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 714fb1ae9f915d04b756f7421c3fbe1c4287e8a6
Author: Sven Schnelle <svens@xxxxxxxxxxxxx>
Date:   Wed Aug 16 17:49:28 2023 +0200

    tracing/synthetic: Allocate one additional element for size
    
    [ Upstream commit c4d6b5438116c184027b2e911c0f2c7c406fb47c ]
    
    While debugging another issue I noticed that the stack trace contains one
    invalid entry at the end:
    
    <idle>-0       [008] d..4.    26.484201: wake_lat: pid=0 delta=2629976084 000000009cc24024 stack=STACK:
    => __schedule+0xac6/0x1a98
    => schedule+0x126/0x2c0
    => schedule_timeout+0x150/0x2c0
    => kcompactd+0x9ca/0xc20
    => kthread+0x2f6/0x3d8
    => __ret_from_fork+0x8a/0xe8
    => 0x6b6b6b6b6b6b6b6b
    
    This is because the code failed to add the one element containing the
    number of entries to field_size.
    
    Link: https://lkml.kernel.org/r/20230816154928.4171614-4-svens@xxxxxxxxxxxxx
    
    Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces")
    Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
    Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index a4c58a932dfa6..32109d092b10f 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -528,7 +528,8 @@ static notrace void trace_event_raw_event_synth(void *__data,
 		str_val = (char *)(long)var_ref_vals[val_idx];
 
 		if (event->dynamic_fields[i]->is_stack) {
-			len = *((unsigned long *)str_val);
+			/* reserve one extra element for size */
+			len = *((unsigned long *)str_val) + 1;
 			len *= sizeof(unsigned long);
 		} else {
 			len = fetch_store_strlen((unsigned long)str_val);