[PATCH 4.5 181/238] tracing: Fix crash from reading trace_pipe with sendfile

From	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	[PATCH 4.5 181/238] tracing: Fix crash from reading trace_pipe with sendfile
Date	2016-04-10 22:30 +0200
Message-ID	<rmu9D-2e3-57@gated-at.bofh.it> (permalink)
References	<rmsr7-Nr-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

4.5-stable review patch.  If anyone has any objections, please let me know.

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

From: Steven Rostedt (Red Hat) <rostedt@goodmis.org>

commit a29054d9478d0435ab01b7544da4f674ab13f533 upstream.

If tracing contains data and the trace_pipe file is read with sendfile(),
then it can trigger a NULL pointer dereference and various BUG_ON within the
VM code.

There's a patch to fix this in the splice_to_pipe() code, but it's also a
good idea to not let that happen from trace_pipe either.

Link: http://lkml.kernel.org/r/1457641146-9068-1-git-send-email-rabin@rab.in

Reported-by: Rabin Vincent <rabin.vincent@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/trace/trace.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4949,7 +4949,10 @@ static ssize_t tracing_splice_read_pipe(
 
 	spd.nr_pages = i;
 
-	ret = splice_to_pipe(pipe, &spd);
+	if (i)
+		ret = splice_to_pipe(pipe, &spd);
+	else
+		ret = 0;
 out:
 	splice_shrink_spd(&spd);
 	return ret;

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

[PATCH 4.5 181/238] tracing: Fix crash from reading trace_pipe with sendfile Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-10 22:30 +0200

csiph-web