From 377ccbb483738f84400ddf5840c7dd8825716985 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 28 Jul 2016 22:30:43 -0400 Subject: Makefile: Mute warning for __builtin_return_address(>0) for tracing only With the latest gcc compilers, they give a warning if __builtin_return_address() parameter is greater than 0. That is because if it is used by a function called by a top level function (or in the case of the kernel, by assembly), it can try to access stack frames outside the stack and crash the system. The tracing system uses __builtin_return_address() of up to 2! But it is well aware of the dangers that it may have, and has even added precautions to protect against it (see the thunk code in arch/x86/entry/thunk*.S) Linus originally added KBUILD_CFLAGS that would suppress the warning for the entire kernel, as simply adding KBUILD_CFLAGS to the tracing directory wouldn't work. The tracing directory plays a bit with the CFLAGS and requires a little more logic. This adds that special logic to only suppress the warning for the tracing directory. If it is used anywhere else outside of tracing, the warning will still be triggered. Link: http://lkml.kernel.org/r/20160728223043.51996267@grimm.local.home Tested-by: Linus Torvalds Signed-off-by: Steven Rostedt --- kernel/trace/Makefile | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/trace') diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 979e7bfbde7a..d0a1617b52b4 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -1,4 +1,8 @@ +# We are fully aware of the dangers of __builtin_return_address() +FRAME_CFLAGS := $(call cc-disable-warning,frame-address) +KBUILD_CFLAGS += $(FRAME_CFLAGS) + # Do not instrument the tracer itself: ifdef CONFIG_FUNCTION_TRACER -- cgit From 47c1856971dd05cac730f70d073518da021b2e5c Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 29 Jun 2016 19:55:59 -0500 Subject: tracing: Fix use-after-free in hist_unreg_all/hist_enable_unreg_all While running tools/testing/selftests test suite with KASAN, Dmitry Vyukov hit the following use-after-free report: ================================================================== BUG: KASAN: use-after-free in hist_unreg_all+0x1a1/0x1d0 at addr ffff880031632cc0 Read of size 8 by task ftracetest/7413 ================================================================== BUG kmalloc-128 (Not tainted): kasan: bad access detected ------------------------------------------------------------------ This fixes the problem, along with the same problem in hist_enable_unreg_all(). Link: http://lkml.kernel.org/r/c3d05b79e42555b6e36a3a99aae0e37315ee5304.1467247517.git.tom.zanussi@linux.intel.com Cc: Dmitry Vyukov [Copied Steve's hist_enable_unreg_all() fix to hist_unreg_all()] Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt --- kernel/trace/trace_events_hist.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 0c05b8a99806..19ae135120a3 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -1500,9 +1500,9 @@ static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops, static void hist_unreg_all(struct trace_event_file *file) { - struct event_trigger_data *test; + struct event_trigger_data *test, *n; - list_for_each_entry_rcu(test, &file->triggers, list) { + list_for_each_entry_safe(test, n, &file->triggers, list) { if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) { list_del_rcu(&test->list); trace_event_trigger_enable_disable(file, 0); @@ -1699,9 +1699,9 @@ hist_enable_get_trigger_ops(char *cmd, char *param) static void hist_enable_unreg_all(struct trace_event_file *file) { - struct event_trigger_data *test; + struct event_trigger_data *test, *n; - list_for_each_entry_rcu(test, &file->triggers, list) { + list_for_each_entry_safe(test, n, &file->triggers, list) { if (test->cmd_ops->trigger_type == ETT_HIST_ENABLE) { list_del_rcu(&test->list); update_cond_flag(file); -- cgit From 7522c03ae307e657114ff909aec650304371a134 Mon Sep 17 00:00:00 2001 From: Tom Zanussi Date: Wed, 29 Jun 2016 19:56:00 -0500 Subject: tracing: Fix use-after-free in hist_register_trigger() This fixes a use-after-free case flagged by KASAN; make sure the test happens before the potential free in this case. Link: http://lkml.kernel.org/r/48fd74ab61bebd7dca9714386bb47d7c5ccd6a7b.1467247517.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt --- kernel/trace/trace_events_hist.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 19ae135120a3..f3a960ed75a1 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -1441,6 +1441,9 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops, goto out; } + if (hist_data->attrs->pause) + data->paused = true; + if (named_data) { destroy_hist_data(data->private_data); data->private_data = named_data->private_data; @@ -1448,9 +1451,6 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops, data->ops = &event_hist_trigger_named_ops; } - if (hist_data->attrs->pause) - data->paused = true; - if (data->ops->init) { ret = data->ops->init(data->ops, data); if (ret < 0) -- cgit