Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-10 22:21:40 +00:00
Code Issues Packages Projects Releases Wiki Activity

tracing/histogram: Don't use strlen to find length of stacktrace variables

Browse Source 
Because stacktraces are saved in dynamic strings,
trace_event_raw_event_synth() uses strlen to determine the length of
the stack.  Stacktraces may contain 0-bytes, though, in the saved
addresses, so the length found and passed to reserve() will be too
small.

Fix this by using the first unsigned long in the stack variables to
store the actual number of elements in the stack and have
trace_event_raw_event_synth() use that to determine the length of the
stack.

Link: https://lkml.kernel.org/r/1ed6906cd9d6477ef2bd8e63c61de20a9ffe64d7.1676063532.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Tom Zanussi 2023-02-10 15:33:03 -06:00 committed by Steven Rostedt (Google)
parent 9c1c251d67
commit fc1a9dc101
2 changed files with 14 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
kernel/trace/trace_events_hist.c
View File

@ -3137,13 +3137,15 @@ static inline void __update_field_vars(struct tracing_map_elt *elt,
size = min(val->size, STR_VAR_LEN_MAX);
strscpy(str, val_str, size);
} else {
char *stack_start = str + sizeof(unsigned long);
int e;
e = stack_trace_save((void *)str,
e = stack_trace_save((void *)stack_start,
HIST_STACKTRACE_DEPTH,
HIST_STACKTRACE_SKIP);
if (e < HIST_STACKTRACE_DEPTH - 1)
((unsigned long *)str)[e] = 0;
((unsigned long *)stack_start)[e] = 0;
*((unsigned long *)str) = e;
}
var_val = (u64)(uintptr_t)str;
}
@ -5135,13 +5137,15 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
size = min(hist_field->size, STR_VAR_LEN_MAX);
strscpy(str, val_str, size);
} else {
char *stack_start = str + sizeof(unsigned long);
int e;
e = stack_trace_save((void *)str,
e = stack_trace_save((void *)stack_start,
HIST_STACKTRACE_DEPTH,
HIST_STACKTRACE_SKIP);
if (e < HIST_STACKTRACE_DEPTH - 1)
((unsigned long *)str)[e] = 0;
((unsigned long *)stack_start)[e] = 0;
*((unsigned long *)str) = e;
}
hist_val = (u64)(uintptr_t)str;
}

7
kernel/trace/trace_events_synth.c
View File

@ -538,7 +538,12 @@ static notrace void trace_event_raw_event_synth(void *__data,
val_idx = var_ref_idx[field_pos];
str_val = (char *)(long)var_ref_vals[val_idx];
len = kern_fetch_store_strlen((unsigned long)str_val);
if (event->dynamic_fields[i]->is_stack) {
len = *((unsigned long *)str_val);
len *= sizeof(unsigned long);
} else {
len = kern_fetch_store_strlen((unsigned long)str_val);
}
fields_size += len;
}