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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2013-07-03 23:33:51 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-29 09:47:34 -0700
commit396dd500521287215d836b84b2ae61cd9163bba5 (patch)
treeffcc34bf6cac2589231fa653e64a6ad80b246527
parent428fbcf9d5d654526a73229d97e76d5d7ac47190 (diff)
tracing/uprobes: Fail to unregister if probe event files are in use
commit c6c2401d8bbaf9edc189b4c35a8cb2780b8b988e upstream. Uprobes suffer the same problem that kprobes have. There's a race between writing to the "enable" file and removing the probe. The probe checks for it being in use and if it is not, goes about deleting the probe and the event that represents it. But the problem with that is, after it checks if it is in use it can be enabled, and the deletion of the event (access to the probe) will fail, as it is in use. But the uprobe will still be deleted. This is a problem as the event can reference the uprobe that was deleted. The fix is to remove the event first, and check to make sure the event removal succeeds. Then it is safe to remove the probe. When the event exists, either ftrace or perf can enable the probe and prevent the event from being removed. Link: http://lkml.kernel.org/r/20130704034038.991525256@goodmis.org Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/trace/trace_uprobe.c51
1 files changed, 38 insertions, 13 deletions
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index d5d0cd368a56..6fd72b768522 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -70,7 +70,7 @@ struct trace_uprobe {
(sizeof(struct probe_arg) * (n)))
static int register_uprobe_event(struct trace_uprobe *tu);
-static void unregister_uprobe_event(struct trace_uprobe *tu);
+static int unregister_uprobe_event(struct trace_uprobe *tu);
static DEFINE_MUTEX(uprobe_lock);
static LIST_HEAD(uprobe_list);
@@ -164,11 +164,17 @@ static struct trace_uprobe *find_probe_event(const char *event, const char *grou
}
/* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
-static void unregister_trace_uprobe(struct trace_uprobe *tu)
+static int unregister_trace_uprobe(struct trace_uprobe *tu)
{
+ int ret;
+
+ ret = unregister_uprobe_event(tu);
+ if (ret)
+ return ret;
+
list_del(&tu->list);
- unregister_uprobe_event(tu);
free_trace_uprobe(tu);
+ return 0;
}
/* Register a trace_uprobe and probe_event */
@@ -181,9 +187,12 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
/* register as an event */
old_tp = find_probe_event(tu->call.name, tu->call.class->system);
- if (old_tp)
+ if (old_tp) {
/* delete old event */
- unregister_trace_uprobe(old_tp);
+ ret = unregister_trace_uprobe(old_tp);
+ if (ret)
+ goto end;
+ }
ret = register_uprobe_event(tu);
if (ret) {
@@ -256,6 +265,8 @@ static int create_trace_uprobe(int argc, char **argv)
group = UPROBE_EVENT_SYSTEM;
if (is_delete) {
+ int ret;
+
if (!event) {
pr_info("Delete command needs an event name.\n");
return -EINVAL;
@@ -269,9 +280,9 @@ static int create_trace_uprobe(int argc, char **argv)
return -ENOENT;
}
/* delete an event */
- unregister_trace_uprobe(tu);
+ ret = unregister_trace_uprobe(tu);
mutex_unlock(&uprobe_lock);
- return 0;
+ return ret;
}
if (argc < 2) {
@@ -408,16 +419,20 @@ fail_address_parse:
return ret;
}
-static void cleanup_all_probes(void)
+static int cleanup_all_probes(void)
{
struct trace_uprobe *tu;
+ int ret = 0;
mutex_lock(&uprobe_lock);
while (!list_empty(&uprobe_list)) {
tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
- unregister_trace_uprobe(tu);
+ ret = unregister_trace_uprobe(tu);
+ if (ret)
+ break;
}
mutex_unlock(&uprobe_lock);
+ return ret;
}
/* Probes listing interfaces */
@@ -462,8 +477,13 @@ static const struct seq_operations probes_seq_op = {
static int probes_open(struct inode *inode, struct file *file)
{
- if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC))
- cleanup_all_probes();
+ int ret;
+
+ if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
+ ret = cleanup_all_probes();
+ if (ret)
+ return ret;
+ }
return seq_open(file, &probes_seq_op);
}
@@ -970,12 +990,17 @@ static int register_uprobe_event(struct trace_uprobe *tu)
return ret;
}
-static void unregister_uprobe_event(struct trace_uprobe *tu)
+static int unregister_uprobe_event(struct trace_uprobe *tu)
{
+ int ret;
+
/* tu->event is unregistered in trace_remove_event_call() */
- trace_remove_event_call(&tu->call);
+ ret = trace_remove_event_call(&tu->call);
+ if (ret)
+ return ret;
kfree(tu->call.print_fmt);
tu->call.print_fmt = NULL;
+ return 0;
}
/* Make a trace interface for controling probe points */