diff mbox series

[2/2] tracing/synthetic: allocate one additional element for size

Message ID 20230809120233.890987-2-svens@linux.ibm.com
State New
Headers
Series [1/2] tracing/synthetic: skip first entry for stack traces |

Commit Message

Sven Schnelle Aug. 9, 2023, 12:02 p.m. UTC 
  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.

Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
---
 kernel/trace/trace_events_synth.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index cf5d0e352810..780ac934058c 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);