From: Steven Rostedt (Google) rostedt@goodmis.org
commit e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c upstream.
Modifiers are used to change the behavior of keys. For instance, they can grouped into buckets, converted to syscall names (from the syscall identifier), show task->comm of the current pid, be an array of longs that represent a stacktrace, and more.
It was found that nothing stopped a value from taking a modifier. As values are simple counters. If this happened, it would call code that was not expecting a modifier and crash the kernel. This was fixed by having the ___create_val_field() function test if a modifier was present and fail if one was. This fixed the crash.
Now there's a problem with variables. Variables are used to pass fields from one event to another. Variables are allowed to have some modifiers, as the processing may need to happen at the time of the event (like stacktraces and comm names of the current pid). The issue is that it too uses __create_val_field(). Now that fails on modifiers, variables can no longer use them (this is a regression).
As not all modifiers are for variables, have them use a separate check.
Link: https://lore.kernel.org/linux-trace-kernel/20230523221108.064a5d82@rorschach...
Cc: stable@vger.kernel.org Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Tom Zanussi zanussi@kernel.org Cc: Mark Rutland mark.rutland@arm.com Fixes: e0213434fe3e4 ("tracing: Do not let histogram values have some modifiers") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/trace/trace_events_hist.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-)
--- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -4238,13 +4238,19 @@ static int __create_val_field(struct his goto out; }
- /* Some types cannot be a value */ - if (hist_field->flags & (HIST_FIELD_FL_GRAPH | HIST_FIELD_FL_PERCENT | - HIST_FIELD_FL_BUCKET | HIST_FIELD_FL_LOG2 | - HIST_FIELD_FL_SYM | HIST_FIELD_FL_SYM_OFFSET | - HIST_FIELD_FL_SYSCALL | HIST_FIELD_FL_STACKTRACE)) { - hist_err(file->tr, HIST_ERR_BAD_FIELD_MODIFIER, errpos(field_str)); - ret = -EINVAL; + /* values and variables should not have some modifiers */ + if (hist_field->flags & HIST_FIELD_FL_VAR) { + /* Variable */ + if (hist_field->flags & (HIST_FIELD_FL_GRAPH | HIST_FIELD_FL_PERCENT | + HIST_FIELD_FL_BUCKET | HIST_FIELD_FL_LOG2)) + goto err; + } else { + /* Value */ + if (hist_field->flags & (HIST_FIELD_FL_GRAPH | HIST_FIELD_FL_PERCENT | + HIST_FIELD_FL_BUCKET | HIST_FIELD_FL_LOG2 | + HIST_FIELD_FL_SYM | HIST_FIELD_FL_SYM_OFFSET | + HIST_FIELD_FL_SYSCALL | HIST_FIELD_FL_STACKTRACE)) + goto err; }
hist_data->fields[val_idx] = hist_field; @@ -4256,6 +4262,9 @@ static int __create_val_field(struct his ret = -EINVAL; out: return ret; + err: + hist_err(file->tr, HIST_ERR_BAD_FIELD_MODIFIER, errpos(field_str)); + return -EINVAL; }
static int create_val_field(struct hist_trigger_data *hist_data,