tracing/synthetic: Allocate one additional element for size

[ Upstream commit c4d6b54381 ]

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@linux.ibm.com

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 00cf3d672a ("tracing: Allow synthetic events to pass around stacktraces")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sven Schnelle 2023-08-16 17:49:28 +02:00 committed by Greg Kroah-Hartman
parent 009e77a916
commit 49834a2c43

View file

@ -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);