From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760410AbbIDQ40 (ORCPT ); Fri, 4 Sep 2015 12:56:26 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:34607 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760250AbbIDQpb (ORCPT ); Fri, 4 Sep 2015 12:45:31 -0400 From: Sasha Levin To: rostedt@goodmis.org, mingo@redhat.com Cc: axboe@fb.com, tj@kernel.org, linux-kernel@vger.kernel.org, Sasha Levin Subject: [PATCH] writeback: verify that underlying dev exists before getting its name Date: Fri, 4 Sep 2015 12:45:18 -0400 Message-Id: <1441385118-27199-1-git-send-email-sasha.levin@oracle.com> X-Mailer: git-send-email 2.1.4 X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We can't assume there is always an underlying device and must verify that as well. Otherwise, we'd deref a NULL ptr here. Signed-off-by: Sasha Levin --- include/trace/events/writeback.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index fff846b..8f9efaa 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -66,7 +66,9 @@ TRACE_EVENT(writeback_dirty_page, TP_fast_assign( strncpy(__entry->name, - mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32); + mapping && inode_to_bdi(mapping->host)->dev ? + dev_name(inode_to_bdi(mapping->host)->dev) : + "(unknown)", 32); __entry->ino = mapping ? mapping->host->i_ino : 0; __entry->index = page->index; ), -- 1.7.10.4