From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755942AbZCED1l (ORCPT ); Wed, 4 Mar 2009 22:27:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753215AbZCED1R (ORCPT ); Wed, 4 Mar 2009 22:27:17 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:43793 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753142AbZCED1P (ORCPT ); Wed, 4 Mar 2009 22:27:15 -0500 Message-Id: <20090305032712.764688306@goodmis.org> References: <20090305032532.802709985@goodmis.org> User-Agent: quilt/0.46-1 Date: Wed, 04 Mar 2009 22:25:34 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Frederic Weisbecker , "H. Peter Anvin" , Theodore Tso , Thomas Gleixner , Steven Rostedt Subject: [PATCH 2/7] tracing: do not return EFAULT if read copied anything Content-Disposition: inline; filename=0002-tracing-do-not-return-EFAULT-if-read-copied-anythin.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt Impact: fix trace read to conform to standards Andrew Morton, Theodore Tso and H. Peter Anvin brought to my attention that a userspace read should not return -EFAULT if it succeeded in copying anything. It should only return -EFAULT if it failed to copy at all. This patch modifies the check of copy_from_user and updates the return code appropriately. I also used H. Peter Anvin's short cut rule to just test ret == count. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 14 ++++++++++++-- 1 files changed, 12 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ab5cbca..57155dc 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -346,6 +346,9 @@ ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt) int len; int ret; + if (!cnt) + return 0; + if (s->len <= s->readpos) return -EBUSY; @@ -353,9 +356,11 @@ ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt) if (cnt > len) cnt = len; ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt); - if (ret) + if (ret == cnt) return -EFAULT; + cnt -= ret; + s->readpos += len; return cnt; } @@ -3049,6 +3054,9 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, ssize_t ret; size_t size; + if (!count) + return 0; + /* Do we have previous read data to read? */ if (info->read < PAGE_SIZE) goto read; @@ -3073,8 +3081,10 @@ read: size = count; ret = copy_to_user(ubuf, info->spare + info->read, size); - if (ret) + if (ret == size) return -EFAULT; + size -= ret; + *ppos += size; info->read += size; -- 1.6.1.3 --