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Commit ea14eb714041d40fcc5180b5a586034503650149

Authored by Steven Rostedt
Committed by Steven Rostedt
1 parent 52fbe9cde7
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

function-graph: Init curr_ret_stack with ret_stack 

If the graph tracer is active, and a task is forked but the allocating of
the processes graph stack fails, it can cause crash later on.

This is due to the temporary stack being NULL, but the curr_ret_stack
variable is copied from the parent. If it is not -1, then in
ftrace_graph_probe_sched_switch() the following:

	for (index = next->curr_ret_stack; index >= 0; index--)
		next->ret_stack[index].calltime += timestamp;

Will cause a kernel OOPS.

Found with Li Zefan's ftrace_stress_test.

Cc: stable@kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Showing 1 changed file with 1 additions and 1 deletions Side-by-side Diff

kernel/trace/ftrace.c
Diff comments   View file @ ea14eb7
... ... @@ -3349,6 +3349,7 @@
3349 3349 {
3350 3350 /* Make sure we do not use the parent ret_stack */
3351 3351 t->ret_stack = NULL;
  3352 + t->curr_ret_stack = -1;
3352 3353  
3353 3354 if (ftrace_graph_active) {
3354 3355 struct ftrace_ret_stack *ret_stack;
... ... @@ -3358,7 +3359,6 @@
3358 3359 GFP_KERNEL);
3359 3360 if (!ret_stack)
3360 3361 return;
3361   - t->curr_ret_stack = -1;
3362 3362 atomic_set(&t->tracing_graph_pause, 0);
3363 3363 atomic_set(&t->trace_overrun, 0);
3364 3364 t->ftrace_timestamp = 0;