From: Beau Belgrave <beaub@linux.microsoft.com>
To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
dcook@linux.microsoft.com
Subject: [PATCH v2 0/2] tracing/user_events: Fix non-spaced field matching
Date: Tue, 23 Apr 2024 16:23:36 +0000 [thread overview]
Message-ID: <20240423162338.292-1-beaub@linux.microsoft.com> (raw)
When the ABI was updated to prevent same name w/different args, it
missed an important corner case when fields don't end with a space.
Typically, space is used for fields to help separate them, like
"u8 field1; u8 field2". If no spaces are used, like
"u8 field1;u8 field2", then the parsing works for the first time.
However, the match check fails on a subsequent register, leading to
confusion.
This is because the match check uses argv_split() and assumes that all
fields will be split upon the space. When spaces are used, we get back
{ "u8", "field1;" }, without spaces we get back { "u8", "field1;u8" }.
This causes a mismatch, and the user program gets back -EADDRINUSE.
Add a method to detect this case before calling argv_split(). If found
force a space after the field separator character ';'. This ensures all
cases work properly for matching.
I could not find an existing function to accomplish this, so I had to
hand code a copy with this logic. If there is a better way to achieve
this, I'm all ears.
This series also adds a selftest to ensure this doesn't break again.
With this fix, the following are all treated as matching:
u8 field1;u8 field2
u8 field1; u8 field2
u8 field1;\tu8 field2
u8 field1;\nu8 field2
V2 changes:
Renamed fix_semis_no_space() to insert_space_after_semis().
Have user_event_argv_split() return fast in no-split case.
Pulled in Masami's shorter loop in insert_space_after_semis().
Beau Belgrave (2):
tracing/user_events: Fix non-spaced field matching
selftests/user_events: Add non-spacing separator check
kernel/trace/trace_events_user.c | 76 ++++++++++++++++++-
.../selftests/user_events/ftrace_test.c | 8 ++
2 files changed, 83 insertions(+), 1 deletion(-)
base-commit: 0bbac3facb5d6cc0171c45c9873a2dc96bea9680
--
2.34.1
next reply other threads:[~2024-04-23 16:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-23 16:23 Beau Belgrave [this message]
2024-04-23 16:23 ` [PATCH v2 1/2] tracing/user_events: Fix non-spaced field matching Beau Belgrave
2024-05-02 21:16 ` Steven Rostedt
2024-05-02 22:58 ` Beau Belgrave
2024-05-02 23:11 ` Steven Rostedt
2024-04-23 16:23 ` [PATCH v2 2/2] selftests/user_events: Add non-spacing separator check Beau Belgrave
2024-05-28 2:08 ` Masami Hiramatsu
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