From: Steven Rostedt (VMware) rostedt@goodmis.org
[ Upstream commit 938aa33f14657c9ed9deea348b7d6f14b6d69cb7 ]
The string copies to the histogram storage has a max size of 256 bytes (defined by MAX_FILTER_STR_VAL). Only the string size of the event field needs to be copied to the event storage, but no more than what is in the event storage. Although nothing should be bigger than 256 bytes, there's no protection against overwriting of the storage if one day there is.
Copy no more than the destination size, and enforce it.
Also had to turn MAX_FILTER_STR_VAL into an unsigned int, to keep the min() comparison of the string sizes of comparable types.
Link: https://lore.kernel.org/all/CAHk-=wjREUihCGrtRBwfX47y_KrLCGjiq3t6QtoNJpmVrAE... Link: https://lkml.kernel.org/r/20211114132834.183429a4@rorschach.local.home
Cc: Ingo Molnar mingo@kernel.org Cc: Andrew Morton akpm@linux-foundation.org Cc: Tom Zanussi zanussi@kernel.org Reported-by: Linus Torvalds torvalds@linux-foundation.org Reviewed-by: Masami Hiramatsu mhiramat@kernel.org Fixes: 63f84ae6b82b ("tracing/histogram: Do not copy the fixed-size char array field over the field size") Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/trace_events.h | 2 +- kernel/trace/trace_events_hist.c | 9 +++++++-- 2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index d321fe5ad1a14..c57b79301a75e 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -571,7 +571,7 @@ struct trace_event_file {
#define PERF_MAX_TRACE_SIZE 2048
-#define MAX_FILTER_STR_VAL 256 /* Should handle KSYM_SYMBOL_LEN */ +#define MAX_FILTER_STR_VAL 256U /* Should handle KSYM_SYMBOL_LEN */
enum event_trigger_type { ETT_NONE = (0), diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 642e4645f6406..c2ec467a5766b 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -2624,8 +2624,10 @@ static inline void __update_field_vars(struct tracing_map_elt *elt, if (val->flags & HIST_FIELD_FL_STRING) { char *str = elt_data->field_var_str[j++]; char *val_str = (char *)(uintptr_t)var_val; + unsigned int size;
- strscpy(str, val_str, val->size); + size = min(val->size, STR_VAR_LEN_MAX); + strscpy(str, val_str, size); var_val = (u64)(uintptr_t)str; } tracing_map_set_var(elt, var_idx, var_val); @@ -4465,6 +4467,7 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data, if (hist_field->flags & HIST_FIELD_FL_STRING) { unsigned int str_start, var_str_idx, idx; char *str, *val_str; + unsigned int size;
str_start = hist_data->n_field_var_str + hist_data->n_save_var_str; @@ -4473,7 +4476,9 @@ 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, hist_field->size); + + size = min(hist_field->size, STR_VAR_LEN_MAX); + strscpy(str, val_str, size);
hist_val = (u64)(uintptr_t)str; }