Commit bef5da60 authored Feb 10, 2017 by Masami Hiramatsu Committed by Steven Rostedt (VMware) Feb 15, 2017

tracing/probes: Fix a warning message to show correct maximum length

Since tracing/*probe_events will accept a probe definition
up to 4096 - 2 ('\n' and '\0') bytes, it must show 4094 instead
of 4096 in warning message.

Note that there is one possible case of exceed 4094. If user
prepare 4096 bytes null-terminated string and syscall write
it with the count == 4095, then it can be accepted. However,
if user puts a '\n' after that, it must rejected.
So IMHO, the warning message should indicate shorter one,
since it is safer.

Link: http://lkml.kernel.org/r/148673290462.2579.7966778294009665632.stgit@devbox



Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent 8f0994bb

kernel/trace/trace_probe.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -679,8 +679,9 @@ ssize_t traceprobe_probes_write(struct file file, const char __user buffer,
		if (done + size < count) {
		if (buf != kbuf)
		break;
		/* This can accept WRITE_BUFSIZE - 2 ('\n' + '\0') */
		pr_warn("Line length is too long: Should be less than %d\n",
		WRITE_BUFSIZE);
		WRITE_BUFSIZE - 2);
		ret = -EINVAL;
		goto out;
		}