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tracing: Remove check of list iterator against head past the loop body

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When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.

While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&pos->member == head, using the iterator variable after the loop should
be avoided.

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Link: https://lkml.kernel.org/r/20220427170734.819891-5-jakobkoschel@gmail.com

Cc: Ingo Molnar <mingo@redhat.com>
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Jakob Koschel 2022-04-27 19:07:34 +02:00 • committed by Steven Rostedt (Google)
parent 45e333ce2a
commit ba27d85558
3 changed files with 26 additions and 20 deletions
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14
kernel/trace/trace_eprobe.c
View file

@ -648,7 +648,7 @@ static struct trace_event_functions eprobe_funcs = {
static int disable_eprobe(struct trace_eprobe *ep,
struct trace_array *tr)
{
struct event_trigger_data *trigger;
struct event_trigger_data *trigger = NULL, *iter;
struct trace_event_file *file;
struct eprobe_data *edata;
@ -656,14 +656,16 @@ static int disable_eprobe(struct trace_eprobe *ep,
if (!file)
return -ENOENT;
list_for_each_entry(trigger, &file->triggers, list) {
if (!(trigger->flags & EVENT_TRIGGER_FL_PROBE))
list_for_each_entry(iter, &file->triggers, list) {
if (!(iter->flags & EVENT_TRIGGER_FL_PROBE))
continue;
edata = trigger->private_data;
if (edata->ep == ep)
edata = iter->private_data;
if (edata->ep == ep) {
trigger = iter;
break;
}
}
if (list_entry_is_head(trigger, &file->triggers, list))
if (!trigger)
return -ENODEV;
list_del_rcu(&trigger->list);