summaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorNamhyung Kim <namhyung@kernel.org>2017-04-17 11:44:27 +0900
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-04-21 09:31:22 +0200
commit7da0f8e547c2d3cac939da24458a88cce550af11 (patch)
tree9083bebc537667c9542b59000847699a9a356754 /kernel
parente3c7258bb4fe5b509621ce643f096502dceec8a4 (diff)
ftrace: Fix function pid filter on instances
commit d879d0b8c183aabeb9a65eba91f3f9e3c7e7b905 upstream. When function tracer has a pid filter, it adds a probe to sched_switch to track if current task can be ignored. The probe checks the ftrace_ignore_pid from current tr to filter tasks. But it misses to delete the probe when removing an instance so that it can cause a crash due to the invalid tr pointer (use-after-free). This is easily reproducible with the following: # cd /sys/kernel/debug/tracing # mkdir instances/buggy # echo $$ > instances/buggy/set_ftrace_pid # rmdir instances/buggy ============================================================================ BUG: KASAN: use-after-free in ftrace_filter_pid_sched_switch_probe+0x3d/0x90 Read of size 8 by task kworker/0:1/17 CPU: 0 PID: 17 Comm: kworker/0:1 Tainted: G B 4.11.0-rc3 #198 Call Trace: dump_stack+0x68/0x9f kasan_object_err+0x21/0x70 kasan_report.part.1+0x22b/0x500 ? ftrace_filter_pid_sched_switch_probe+0x3d/0x90 kasan_report+0x25/0x30 __asan_load8+0x5e/0x70 ftrace_filter_pid_sched_switch_probe+0x3d/0x90 ? fpid_start+0x130/0x130 __schedule+0x571/0xce0 ... To fix it, use ftrace_clear_pids() to unregister the probe. As instance_rmdir() already updated ftrace codes, it can just free the filter safely. Link: http://lkml.kernel.org/r/20170417024430.21194-2-namhyung@kernel.org Fixes: 0c8916c34203 ("tracing: Add rmdir to remove multibuffer instances") Cc: Ingo Molnar <mingo@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ftrace.c9
-rw-r--r--kernel/trace/trace.c1
-rw-r--r--kernel/trace/trace.h2
3 files changed, 12 insertions, 0 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3bd975c8d9c9..221eb59272e1 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5401,6 +5401,15 @@ static void clear_ftrace_pids(struct trace_array *tr)
trace_free_pid_list(pid_list);
}
+void ftrace_clear_pids(struct trace_array *tr)
+{
+ mutex_lock(&ftrace_lock);
+
+ clear_ftrace_pids(tr);
+
+ mutex_unlock(&ftrace_lock);
+}
+
static void ftrace_pid_reset(struct trace_array *tr)
{
mutex_lock(&ftrace_lock);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 90b66ed6f0e2..862bc8805d97 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7150,6 +7150,7 @@ static int instance_rmdir(const char *name)
tracing_set_nop(tr);
event_trace_del_tracer(tr);
+ ftrace_clear_pids(tr);
ftrace_destroy_function_files(tr);
tracefs_remove_recursive(tr->dir);
free_trace_buffers(tr);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index fd24b1f9ac43..b0d8576c27ae 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -870,6 +870,7 @@ int using_ftrace_ops_list_func(void);
void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer);
void ftrace_init_tracefs_toplevel(struct trace_array *tr,
struct dentry *d_tracer);
+void ftrace_clear_pids(struct trace_array *tr);
#else
static inline int ftrace_trace_task(struct trace_array *tr)
{
@@ -888,6 +889,7 @@ ftrace_init_global_array_ops(struct trace_array *tr) { }
static inline void ftrace_reset_array_ops(struct trace_array *tr) { }
static inline void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d) { }
static inline void ftrace_init_tracefs_toplevel(struct trace_array *tr, struct dentry *d) { }
+static inline void ftrace_clear_pids(struct trace_array *tr) { }
/* ftace_func_t type is not defined, use macro instead of static inline */
#define ftrace_init_array_ops(tr, func) do { } while (0)
#endif /* CONFIG_FUNCTION_TRACER */