aboutsummaryrefslogtreecommitdiffstats
path: root/kernel
diff options
context:
space:
mode:
authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2013-07-03 23:33:51 -0400
committerSteven Rostedt <rostedt@goodmis.org>2013-08-01 18:25:50 -0400
commitc6c2401d8bbaf9edc189b4c35a8cb2780b8b988e (patch)
tree5589795f4b86670b2d4f4851a4de8f1401c6c7ff /kernel
parenttracing/kprobes: Fail to unregister if probe event files are in use (diff)
downloadlinux-dev-c6c2401d8bbaf9edc189b4c35a8cb2780b8b988e.tar.xz
linux-dev-c6c2401d8bbaf9edc189b4c35a8cb2780b8b988e.zip
tracing/uprobes: Fail to unregister if probe event files are in use
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>
Diffstat (limited to 'kernel')
-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 a23d2d71188e..272261b5f94f 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);
}
@@ -968,12 +988,17 @@ 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 */