From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754534Ab1BFXpx (ORCPT ); Sun, 6 Feb 2011 18:45:53 -0500 Received: from 1wt.eu ([62.212.114.60]:60293 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754519Ab1BFXpv (ORCPT ); Sun, 6 Feb 2011 18:45:51 -0500 Message-Id: <20110206232253.378726212@pcw.home.local> User-Agent: quilt/0.48-1 Date: Mon, 07 Feb 2011 00:23:12 +0100 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@kernel.org, stable-review@kernel.org Cc: Slava Pestov , Steven Rostedt , Greg Kroah-Hartman , Willy Tarreau Subject: [PATCH 20/23] tracing: Fix panic when lseek() called on "trace" opened for writing In-Reply-To: <4beed4da27f06efb2c13d6ed48850634@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27.58-stable review patch. If anyone has any objections, please let us know. ------------------ From: Slava Pestov commit 364829b1263b44aa60383824e4c1289d83d78ca7 upstream. The file_ops struct for the "trace" special file defined llseek as seq_lseek(). However, if the file was opened for writing only, seq_open() was not called, and the seek would dereference a null pointer, file->private_data. This patch introduces a new wrapper for seq_lseek() which checks if the file descriptor is opened for reading first. If not, it does nothing. Signed-off-by: Slava Pestov LKML-Reference: <1290640396-24179-1-git-send-email-slavapestov@google.com> Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman [wt: applied to tracing_lt_fops too /wt] Signed-off-by: Willy Tarreau --- kernel/trace/trace.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) Index: longterm-2.6.27/kernel/trace/trace.c =================================================================== --- longterm-2.6.27.orig/kernel/trace/trace.c 2011-01-23 10:52:37.000000000 +0100 +++ longterm-2.6.27/kernel/trace/trace.c 2011-01-29 11:42:07.287067215 +0100 @@ -2041,17 +2041,25 @@ return ret; } +static loff_t tracing_seek(struct file *file, loff_t offset, int origin) +{ + if (file->f_mode & FMODE_READ) + return seq_lseek(file, offset, origin); + else + return 0; +} + static struct file_operations tracing_fops = { .open = tracing_open, .read = seq_read, - .llseek = seq_lseek, + .llseek = tracing_lseek, .release = tracing_release, }; static struct file_operations tracing_lt_fops = { .open = tracing_lt_open, .read = seq_read, - .llseek = seq_lseek, + .llseek = tracing_lseek, .release = tracing_release, };