This is a note to let you know that I've just added the patch titled tracing/histogram: Do not copy the fixed-size char array field over the field size to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tracing-histogram-do-not-copy-the-fixed-size-char-ar.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 12ef293e7ba0ec193e886b6d888e6fba4c991dbe Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Date: Sat Nov 13 01:02:08 2021 +0900 tracing/histogram: Do not copy the fixed-size char array field over the field size [ Upstream commit 63f84ae6b82bb4dff672f76f30c6fd7b9d3766bc ] 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: 02205a6752f2 (tracing: Add support for 'field variables') Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 9a73c187d241e..8b33a3c872750 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -2590,9 +2590,10 @@ 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; @@ -3530,7 +3531,7 @@ 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); @@ -5359,7 +5360,7 @@ 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; }