From: Steven Rostedt (Red Hat) Date: Fri, 18 Mar 2016 19:46:48 +0000 (-0400) Subject: tracing: Fix crash from reading trace_pipe with sendfile X-Git-Tag: v3.10.102~99 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3f3f1fce3c1af5720308ec83a3d2ffb328a028aa;p=thirdparty%2Fkernel%2Fstable.git tracing: Fix crash from reading trace_pipe with sendfile 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 Cc: stable@vger.kernel.org # 2.6.30+ Reported-by: Rabin Vincent Signed-off-by: Steven Rostedt Signed-off-by: Willy Tarreau --- diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 640e4c44b1701..eff26a976f024 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;