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tracing/histogram: Do not copy the fixed-size char array field over the field size

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Do not copy the fixed-size char array field of the events over
the field size. The histogram treats char array as a string and
there are 2 types of char array in the event, fixed-size and
dynamic string. The dynamic string (__data_loc) field must be
null terminated, but the fixed-size char array field may not
be null terminated (not a string, but just a data).
In that case, histogram can copy the data after the field.
This uses the original field size for fixed-size char array
field to restrict the histogram not to access over the original
field size.

Link: https://lkml.kernel.org/r/163673292822.195747.3696966210526410250.stgit@devnote2

Fixes: 02205a6752 (tracing: Add support for 'field variables')
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu 2021-11-13 01:02:08 +09:00 committed by Steven Rostedt (VMware)
parent d7458bc0d8
commit 63f84ae6b8
1 changed files with 5 additions and 4 deletions
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9
kernel/trace/trace_events_hist.c
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@ -1953,9 +1953,10 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
if (!hist_field->type)
goto free;
if (field->filter_type == FILTER_STATIC_STRING)
if (field->filter_type == FILTER_STATIC_STRING) {
hist_field->fn = hist_field_string;
else if (field->filter_type == FILTER_DYN_STRING)
hist_field->size = field->size;
} else if (field->filter_type == FILTER_DYN_STRING)
hist_field->fn = hist_field_dynstring;
else
hist_field->fn = hist_field_pstring;
@ -3025,7 +3026,7 @@ static inline void __update_field_vars(struct tracing_map_elt *elt,
char *str = elt_data->field_var_str[j++];
char *val_str = (char *)(uintptr_t)var_val;
strscpy(str, val_str, STR_VAR_LEN_MAX);
strscpy(str, val_str, val->size);
var_val = (u64)(uintptr_t)str;
}
tracing_map_set_var(elt, var_idx, var_val);
@ -4920,7 +4921,7 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
str = elt_data->field_var_str[idx];
val_str = (char *)(uintptr_t)hist_val;
strscpy(str, val_str, STR_VAR_LEN_MAX);
strscpy(str, val_str, hist_field->size);
hist_val = (u64)(uintptr_t)str;
}