ftrace: Handle commands when closing set_ftrace_filter file

stable inclusion
from stable-5.10.36
commit 634684d79733124f7470b226b0f42aada4426b07
bugzilla: 51867
CVE: NA

--------------------------------

commit 8c9af478 upstream.

 # echo switch_mm:traceoff > /sys/kernel/tracing/set_ftrace_filter

will cause switch_mm to stop tracing by the traceoff command.

 # echo -n switch_mm:traceoff > /sys/kernel/tracing/set_ftrace_filter

does nothing.

The reason is that the parsing in the write function only processes
commands if it finished parsing (there is white space written after the
command). That's to handle:

 write(fd, "switch_mm:", 10);
 write(fd, "traceoff", 8);

cases, where the command is broken over multiple writes.

The problem is if the file descriptor is closed, then the write call is
not processed, and the command needs to be processed in the release code.
The release code can handle matching of functions, but does not handle
commands.

Cc: stable@vger.kernel.org
Fixes: eda1e328 ("tracing: handle broken names in ftrace filter")
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/trace/ftrace.c

@@ -5632,7 +5632,10 @@ int ftrace_regex_release(struct inode *inode, struct file *file)
 
 	parser = &iter->parser;
 	if (trace_parser_loaded(parser)) {
-		ftrace_match_records(iter->hash, parser->buffer, parser->idx);
+		int enable = !(iter->flags & FTRACE_ITER_NOTRACE);
+
+		ftrace_process_regex(iter, parser->buffer,
+				     parser->idx, enable);
 	}
 
 	trace_parser_put(parser);