In check_synth_field(), when a synthetic event field is a stacktrace
(field->is_stack) and the histogram field is not a "long[" stacktrace
array, validation falls through to the generic size and signedness
comparison.
Because parse_synth_field() sets a stacktrace field's type to
"__data_loc unsigned long[]", its size is sizeof(u64) and
synth_field_signed() marks it as signed. Consequently, any 8-byte
signed scalar histogram field passes the fallback check, and its scalar
value is subsequently dereferenced as a kernel stacktrace pointer in
get_field_size() and trace_stack().
Furthermore, checking strstr(hist_field->type, "long[") is insufficient
because tracepoint fields defined with __bitmask() or __rel_bitmask()
also have type "__data_loc unsigned long[]" or "__rel_loc unsigned
long[]", whilst create_hist_field() treats them as 4-byte scalar values
without HIST_FIELD_FL_STACKTRACE.
Propagate HIST_FIELD_FL_STACKTRACE to variable references and field
variables (whilst excluding variable aliases from per-element
stacktrace capture), and reject any mismatch between
HIST_FIELD_FL_STACKTRACE and field->is_stack in check_synth_field().
Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around
stacktraces")
Cc: [email protected]
Signed-off-by: Lee Jones <[email protected]>
---
v1 -> v2:
- Check HIST_FIELD_FL_STACKTRACE instead of strstr(hist_field->type, "long[")
so __bitmask() and __rel_bitmask() fields are also rejected.
- Propagate HIST_FIELD_FL_STACKTRACE to variable references and field
variables, whilst excluding variable aliases from per-element stacktrace
capture.
kernel/trace/trace_events_hist.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 8af97fd4ee2d..d8864b3165d2 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -2121,7 +2121,8 @@ static int init_var_ref(struct hist_field *ref_field,
ref_field->size = var_field->size;
ref_field->is_signed = var_field->is_signed;
ref_field->flags |= var_field->flags &
- (HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
+ (HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS |
+ HIST_FIELD_FL_STACKTRACE);
if (system) {
ref_field->system = kstrdup(system, GFP_KERNEL);
@@ -3318,6 +3319,7 @@ static struct field_var *create_field_var(struct
hist_trigger_data *hist_data,
ret = PTR_ERR(var);
goto err;
}
+ var->flags |= val->flags & HIST_FIELD_FL_STACKTRACE;
field_var = kzalloc_obj(struct field_var);
if (!field_var) {
@@ -3946,7 +3948,10 @@ static int check_synth_field(struct synth_event *event,
&& field->is_dynamic)
return 0;
- if (strstr(hist_field->type, "long[") && field->is_stack)
+ if (!!(hist_field->flags & HIST_FIELD_FL_STACKTRACE) != field->is_stack)
+ return -EINVAL;
+
+ if (field->is_stack)
return 0;
if (strcmp(field->type, hist_field->type) != 0) {
@@ -4487,7 +4492,8 @@ static int create_var_field(struct hist_trigger_data
*hist_data,
if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_EXECNAME)
update_var_execname(hist_data->fields[val_idx]);
- if (!ret && hist_data->fields[val_idx]->flags &
+ if (!ret && !(hist_data->fields[val_idx]->flags & HIST_FIELD_FL_ALIAS)
&&
+ hist_data->fields[val_idx]->flags &
(HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE))
hist_data->fields[val_idx]->var_str_idx =
hist_data->n_var_str++;
@@ -5228,7 +5234,8 @@ static void hist_trigger_elt_update(struct
hist_trigger_data *hist_data,
if (hist_field->flags & HIST_FIELD_FL_VAR) {
var_idx = hist_field->var.idx;
- if (hist_field->flags &
+ if (!(hist_field->flags & HIST_FIELD_FL_ALIAS) &&
+ hist_field->flags &
(HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE)) {
unsigned int str_start, var_str_idx, idx;
char *str, *val_str;
--
2.56.0.385.gd3acb90ef8-goog
