rv: Use strings in da monitors tracepoints

Using DA monitors tracepoints with KASAN enabled triggers the following
warning:

 BUG: KASAN: global-out-of-bounds in do_trace_event_raw_event_event_da_monitor+0xd6/0x1a0
 Read of size 32 at addr ffffffffaada8980 by task ...
 Call Trace:
  <TASK>
 [...]
  do_trace_event_raw_event_event_da_monitor+0xd6/0x1a0
  ? __pfx_do_trace_event_raw_event_event_da_monitor+0x10/0x10
  ? trace_event_sncid+0x83/0x200
  trace_event_sncid+0x163/0x200
 [...]
 The buggy address belongs to the variable:
  automaton_snep+0x4e0/0x5e0

This is caused by the tracepoints reading 32 bytes __array instead of
__string from the automata definition. Such strings are literals and
reading 32 bytes ends up in out of bound memory accesses (e.g. the next
automaton's data in this case).
The error is harmless as, while printing the string, we stop at the null
terminator, but it should still be fixed.

Use the __string facilities while defining the tracepoints to avoid
reading out of bound memory.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tomas Glozar <tglozar@redhat.com>
Cc: Juri Lelli <jlelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Link: https://lore.kernel.org/20250728135022.255578-4-gmonaco@redhat.com
Fixes: 792575348ff7 ("rv/include: Add deterministic automata monitor definition via C macros")
Reviewed-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/rv/rv_trace.h b/kernel/trace/rv/rv_trace.h
index 17ba07329b670ac3746b63f34036e45f315079fb..d38e0d3abdfde5e2ae90712da872d0e5d5d5ec60 100644 (file)
--- a/kernel/trace/rv/rv_trace.h
+++ b/kernel/trace/rv/rv_trace.h
@@ -16,23 +16,23 @@ DECLARE_EVENT_CLASS(event_da_monitor,
        TP_ARGS(state, event, next_state, final_state),
 
        TP_STRUCT__entry(
-               __array(        char,   state,          MAX_DA_NAME_LEN )
-               __array(        char,   event,          MAX_DA_NAME_LEN )
-               __array(        char,   next_state,     MAX_DA_NAME_LEN )
-               __field(        bool,   final_state                     )
+               __string(       state,          state           )
+               __string(       event,          event           )
+               __string(       next_state,     next_state      )
+               __field(        bool,           final_state     )
        ),
 
        TP_fast_assign(
-               memcpy(__entry->state,          state,          MAX_DA_NAME_LEN);
-               memcpy(__entry->event,          event,          MAX_DA_NAME_LEN);
-               memcpy(__entry->next_state,     next_state,     MAX_DA_NAME_LEN);
-               __entry->final_state            = final_state;
+               __assign_str(state);
+               __assign_str(event);
+               __assign_str(next_state);
+               __entry->final_state = final_state;
        ),
 
        TP_printk("%s x %s -> %s%s",
-               __entry->state,
-               __entry->event,
-               __entry->next_state,
+               __get_str(state),
+               __get_str(event),
+               __get_str(next_state),
                __entry->final_state ? " (final)" : "")
 );
 
@@ -43,18 +43,18 @@ DECLARE_EVENT_CLASS(error_da_monitor,
        TP_ARGS(state, event),
 
        TP_STRUCT__entry(
-               __array(        char,   state,          MAX_DA_NAME_LEN )
-               __array(        char,   event,          MAX_DA_NAME_LEN )
+               __string(       state,  state   )
+               __string(       event,  event   )
        ),
 
        TP_fast_assign(
-               memcpy(__entry->state,          state,          MAX_DA_NAME_LEN);
-               memcpy(__entry->event,          event,          MAX_DA_NAME_LEN);
+               __assign_str(state);
+               __assign_str(event);
        ),
 
        TP_printk("event %s not expected in the state %s",
-               __entry->event,
-               __entry->state)
+               __get_str(event),
+               __get_str(state))
 );
 
 #include <monitors/wip/wip_trace.h>
@@ -75,26 +75,26 @@ DECLARE_EVENT_CLASS(event_da_monitor_id,
        TP_ARGS(id, state, event, next_state, final_state),
 
        TP_STRUCT__entry(
-               __field(        int,    id                              )
-               __array(        char,   state,          MAX_DA_NAME_LEN )
-               __array(        char,   event,          MAX_DA_NAME_LEN )
-               __array(        char,   next_state,     MAX_DA_NAME_LEN )
-               __field(        bool,   final_state                     )
+               __field(        int,            id              )
+               __string(       state,          state           )
+               __string(       event,          event           )
+               __string(       next_state,     next_state      )
+               __field(        bool,           final_state     )
        ),
 
        TP_fast_assign(
-               memcpy(__entry->state,          state,          MAX_DA_NAME_LEN);
-               memcpy(__entry->event,          event,          MAX_DA_NAME_LEN);
-               memcpy(__entry->next_state,     next_state,     MAX_DA_NAME_LEN);
-               __entry->id                     = id;
-               __entry->final_state            = final_state;
+               __assign_str(state);
+               __assign_str(event);
+               __assign_str(next_state);
+               __entry->id             = id;
+               __entry->final_state    = final_state;
        ),
 
        TP_printk("%d: %s x %s -> %s%s",
                __entry->id,
-               __entry->state,
-               __entry->event,
-               __entry->next_state,
+               __get_str(state),
+               __get_str(event),
+               __get_str(next_state),
                __entry->final_state ? " (final)" : "")
 );
 
@@ -105,21 +105,21 @@ DECLARE_EVENT_CLASS(error_da_monitor_id,
        TP_ARGS(id, state, event),
 
        TP_STRUCT__entry(
-               __field(        int,    id                              )
-               __array(        char,   state,          MAX_DA_NAME_LEN )
-               __array(        char,   event,          MAX_DA_NAME_LEN )
+               __field(        int,    id      )
+               __string(       state,  state   )
+               __string(       event,  event   )
        ),
 
        TP_fast_assign(
-               memcpy(__entry->state,          state,          MAX_DA_NAME_LEN);
-               memcpy(__entry->event,          event,          MAX_DA_NAME_LEN);
-               __entry->id                     = id;
+               __assign_str(state);
+               __assign_str(event);
+               __entry->id     = id;
        ),
 
        TP_printk("%d: event %s not expected in the state %s",
                __entry->id,
-               __entry->event,
-               __entry->state)
+               __get_str(event),
+               __get_str(state))
 );
 
 #include <monitors/wwnr/wwnr_trace.h>