tracing: Fix parsing of globs with a wildcard at the beginning
authorSteven Rostedt (VMware) <rostedt@goodmis.org>
Tue, 6 Feb 2018 03:18:11 +0000 (22:18 -0500)
committerSteven Rostedt (VMware) <rostedt@goodmis.org>
Thu, 8 Feb 2018 15:11:47 +0000 (10:11 -0500)
commit07234021410bbc27b7c86c18de98616c29fbe667
treee9e4e58e5a3ec3b8ab8b35811f1a2935795828bf
parent7b6586562708d2b3a04fe49f217ddbadbbbb0546
tracing: Fix parsing of globs with a wildcard at the beginning

Al Viro reported:

    For substring - sure, but what about something like "*a*b" and "a*b"?
    AFAICS, filter_parse_regex() ends up with identical results in both
    cases - MATCH_GLOB and *search = "a*b".  And no way for the caller
    to tell one from another.

Testing this with the following:

 # cd /sys/kernel/tracing
 # echo '*raw*lock' > set_ftrace_filter
 bash: echo: write error: Invalid argument

With this patch:

 # echo '*raw*lock' > set_ftrace_filter
 # cat set_ftrace_filter
_raw_read_trylock
_raw_write_trylock
_raw_read_unlock
_raw_spin_unlock
_raw_write_unlock
_raw_spin_trylock
_raw_spin_lock
_raw_write_lock
_raw_read_lock

Al recommended not setting the search buffer to skip the first '*' unless we
know we are not using MATCH_GLOB. This implements his suggested logic.

Link: http://lkml.kernel.org/r/20180127170748.GF13338@ZenIV.linux.org.uk
Cc: stable@vger.kernel.org
Fixes: 60f1d5e3bac44 ("ftrace: Support full glob matching")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Suggsted-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
kernel/trace/trace_events_filter.c