Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dave Chinner , Brian Foster , Dave Chinner Subject: [PATCH 3.19 014/175] xfs: only trace buffer items if they exist Date: Tue, 3 Mar 2015 22:13:12 -0800 Message-Id: <20150304061028.727665091@linuxfoundation.org> In-Reply-To: <20150304061026.134125919@linuxfoundation.org> References: <20150304061026.134125919@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dave Chinner commit e9892d3cc853afdda2cc69e2576d9ddb5fafad71 upstream. The commit 2d3d0c5 ("xfs: lobotomise xfs_trans_read_buf_map()") left a landmine in the tracing code: trace_xfs_trans_buf_read() is now call on all buffers that are read through this interface rather than just buffers in transactions. For buffers outside transaction context, bp->b_fspriv is null, and so the buf log item tracing functions cannot be called. This causes a NULL pointer dereference in the trace_xfs_trans_buf_read() function when tracing is turned on. Signed-off-by: Dave Chinner Reviewed-by: Brian Foster Signed-off-by: Dave Chinner Signed-off-by: Greg Kroah-Hartman --- fs/xfs/xfs_trans_buf.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/fs/xfs/xfs_trans_buf.c +++ b/fs/xfs/xfs_trans_buf.c @@ -327,9 +327,10 @@ xfs_trans_read_buf_map( return -EIO; } - if (tp) + if (tp) { _xfs_trans_bjoin(tp, bp, 1); - trace_xfs_trans_read_buf(bp->b_fspriv); + trace_xfs_trans_read_buf(bp->b_fspriv); + } *bpp = bp; return 0;