user/sven/linux.git/kernel/trace/trace_events_trigger.c, branch v6.6.65

tracing: Have format file honor EVENT_FILE_FL_FREED

2024-09-04T11:28:22Z

commit b1560408692cd0ab0370cfbe9deb03ce97ab3f6d upstream. When eventfs was introduced, special care had to be done to coordinate the freeing of the file meta data with the files that are exposed to user space. The file meta data would have a ref count that is set when the file is created and would be decremented and freed after the last user that opened the file closed it. When the file meta data was to be freed, it would set a flag (EVENT_FILE_FL_FREED) to denote that the file is freed, and any new references made (like new opens or reads) would fail as it is marked freed. This allowed other meta data to be freed after this flag was set (under the event_mutex). All the files that were dynamically created in the events directory had a pointer to the file meta data and would call event_release() when the last reference to the user space file was closed. This would be the time that it is safe to free the file meta data. A shortcut was made for the "format" file. It's i_private would point to the "call" entry directly and not point to the file's meta data. This is because all format files are the same for the same "call", so it was thought there was no reason to differentiate them. The other files maintain state (like the "enable", "trigger", etc). But this meant if the file were to disappear, the "format" file would be unaware of it. This caused a race that could be trigger via the user_events test (that would create dynamic events and free them), and running a loop that would read the user_events format files: In one console run: # cd tools/testing/selftests/user_events # while true; do ./ftrace_test; done And in another console run: # cd /sys/kernel/tracing/ # while true; do cat events/user_events/__test_event/format; done 2>/dev/null With KASAN memory checking, it would trigger a use-after-free bug report (which was a real bug). This was because the format file was not checking the file's meta data flag "EVENT_FILE_FL_FREED", so it would access the event that the file meta data pointed to after the event was freed. After inspection, there are other locations that were found to not check the EVENT_FILE_FL_FREED flag when accessing the trace_event_file. Add a new helper function: event_file_file() that will make sure that the event_mutex is held, and will return NULL if the trace_event_file has the EVENT_FILE_FL_FREED flag set. Have the first reference of the struct file pointer use event_file_file() and check for NULL. Later uses can still use the event_file_data() helper function if the event_mutex is still held and was not released since the event_file_file() call. Link: https://lore.kernel.org/all/20240719204701.1605950-1-minipli@grsecurity.net/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Ajay Kaher Cc: Ilkka Naulapää Cc: Linus Torvalds Cc: Al Viro Cc: Dan Carpenter Cc: Beau Belgrave Cc: Florian Fainelli Cc: Alexey Makhalov Cc: Vasavi Sirnapalli Link: https://lore.kernel.org/20240730110657.3b69d3c1@gandalf.local.home Fixes: b63db58e2fa5d ("eventfs/tracing: Add callback for release of an eventfs_inode") Reported-by: Mathias Krause Tested-by: Mathias Krause Signed-off-by: Steven Rostedt (Google) [Resolve conflict due to lack of commit a1f157c7a3bb ("tracing: Expand all ring buffers individually") which add tracing_update_buffers() in event_enable_write(), that commit is more of a feature than a bugfix and is not related to the problem fixed by this patch] Signed-off-by: Zheng Yejian Signed-off-by: Greg Kroah-Hartman

tracing/trigger: Fix to return error if failed to alloc snapshot

2024-02-23T08:24:54Z

commit 0958b33ef5a04ed91f61cef4760ac412080c4e08 upstream. Fix register_snapshot_trigger() to return error code if it failed to allocate a snapshot instead of 0 (success). Unless that, it will register snapshot trigger without an error. Link: https://lore.kernel.org/linux-trace-kernel/170622977792.270660.2789298642759362200.stgit@devnote2 Fixes: 0bbe7f719985 ("tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation") Cc: stable@vger.kernel.org Cc: Vincent Donnefort Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

tracing: Fix kernel-doc warnings in trace_events_trigger.c

2023-07-28T23:59:03Z

Fix kernel-doc warnings: kernel/trace/trace_events_trigger.c:59: warning: Function parameter or member 'buffer' not described in 'event_triggers_call' kernel/trace/trace_events_trigger.c:59: warning: Function parameter or member 'event' not described in 'event_triggers_call' Link: https://lkml.kernel.org/r/20230724140827.1023266-4-cuigaosheng1@huawei.com Cc: Signed-off-by: Gaosheng Cui Signed-off-by: Steven Rostedt (Google)

tracing: Do not synchronize freeing of trigger filter on boot up

2022-12-14T13:50:56Z

If a trigger filter on the kernel command line fails to apply (due to syntax error), it will be freed. The freeing will call tracepoint_synchronize_unregister(), but this is not needed during early boot up, and will even trigger a lockdep splat. Avoid calling the synchronization function when system_state is SYSTEM_BOOTING. Link: https://lore.kernel.org/linux-trace-kernel/20221213172429.7774f4ba@gandalf.local.home Cc: Andrew Morton Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google)

tracing: Have trigger filter parsing errors show up in error_log

2022-12-13T20:46:05Z

It is annoying that the filter parsing of triggers do not show up in the error_log. Trying to figure out what is incorrect in the input is difficult when it fails for a typo. Have the errors of filter parsing show up in error_log as well. Link: https://lore.kernel.org/linux-trace-kernel/20221213095602.083fa9fd@gandalf.local.home Cc: Masami Hiramatsu Cc: Tom Zanussi Signed-off-by: Steven Rostedt (Google)

tracing: Fix to check event_mutex is held while accessing trigger list

2022-09-07T02:26:00Z

Since the check_user_trigger() is called outside of RCU read lock, this list_for_each_entry_rcu() caused a suspicious RCU usage warning. # echo hist:keys=pid > events/sched/sched_stat_runtime/trigger # cat events/sched/sched_stat_runtime/trigger [ 43.167032] [ 43.167418] ============================= [ 43.167992] WARNING: suspicious RCU usage [ 43.168567] 5.19.0-rc5-00029-g19ebe4651abf #59 Not tainted [ 43.169283] ----------------------------- [ 43.169863] kernel/trace/trace_events_trigger.c:145 RCU-list traversed in non-reader section!! ... However, this file->triggers list is safe when it is accessed under event_mutex is held. To fix this warning, adds a lockdep_is_held check to the list_for_each_entry_rcu(). Link: https://lkml.kernel.org/r/166226474977.223837.1992182913048377113.stgit@devnote2 Cc: stable@vger.kernel.org Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events") Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google)

tracing: Fix comments for event_trigger_separate_filter()

2022-05-27T02:03:52Z

The parameter name in comments of event_trigger_separate_filter() is inconsistent with actual parameter name, fix it. Link: https://lkml.kernel.org/r/20220526072957.165655-1-sunliming@kylinos.cn Signed-off-by: sunliming Signed-off-by: Steven Rostedt (Google)

tracing: Replace usage of found with dedicated list iterator variable

2022-04-27T21:19:31Z

To move the list iterator variable into the list_for_each_entry_*() macro in the future it should be avoided to use the list iterator variable after the loop body. To *never* use the list iterator variable after the loop it was concluded to use a separate iterator variable instead of a found boolean [1]. This removes the need to use a found variable and simply checking if the variable was set, can determine if the break/goto was hit. Link: https://lkml.kernel.org/r/20220427170734.819891-4-jakobkoschel@gmail.com Cc: Ingo Molnar Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1] Signed-off-by: Jakob Koschel Signed-off-by: Steven Rostedt (Google)

tracing: Have existing event_command.parse() implementations use helpers

2022-04-26T21:58:50Z

Simplify the existing event_command.parse() implementations by having them make use of the helper functions previously introduced. Link: https://lkml.kernel.org/r/b353e3427a81f9d3adafd98fd7d73e78a8209f43.1644010576.git.zanussi@kernel.org Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (Google)

tracing: Remove redundant trigger_ops params

2022-04-26T21:58:50Z

Since event_trigger_data contains the .ops trigger_ops field, there's no reason to pass the trigger_ops separately. Remove it as a param from functions whenever event_trigger_data is passed. Link: https://lkml.kernel.org/r/9856c9bc81bde57077f5b8d6f8faa47156c6354a.1644010575.git.zanussi@kernel.org Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (Google)