Path: csiph.com!aioe.org!bofh.it!news.nic.it!robomod From: Steven Rostedt Newsgroups: linux.kernel Subject: [for-next][PATCH 6/8] tracing: Fix crash from reading trace_pipe with sendfile Date: Sat, 19 Mar 2016 15:20:01 +0100 Message-ID: References: X-Original-To: linux-kernel@vger.kernel.org User-Agent: quilt/0.61-1 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=0006-tracing-Fix-crash-from-reading-trace_pipe-with-sendf.patch Sender: robomod@news.nic.it List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Approved: robomod@news.nic.it Lines: 36 Organization: linux.* mail to news gateway X-Original-Cc: Ingo Molnar , Andrew Morton , , Rabin Vincent X-Original-Date: Sat, 19 Mar 2016 10:15:22 -0400 X-Original-Message-ID: <20160319141536.995426051@goodmis.org> X-Original-References: <20160319141516.683762867@goodmis.org> X-Original-Sender: linux-kernel-owner@vger.kernel.org Xref: csiph.com linux.kernel:1361113 From: "Steven Rostedt (Red Hat)" 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 Cc: stable@vger.kernel.org # 2.6.30+ Reported-by: Rabin Vincent Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0ae46048f724..cb2b708e4ea7 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4954,7 +4954,10 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, 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; -- 2.7.0