From: "Steven Rostedt (Red Hat)" <rost...@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-ra...@rab.in Cc: sta...@vger.kernel.org # 2.6.30+ Reported-by: Rabin Vincent <rabin.vinc...@gmail.com> Signed-off-by: Steven Rostedt <rost...@goodmis.org> Signed-off-by: Willy Tarreau <w...@1wt.eu> --- 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 640e4c4..eff26a9 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4351,7 +4351,10 @@ 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; -- 2.8.0.rc2.1.gbe9624a
