From: Jan Blunck Subject: [PATCH] sg.c: fix a memory leak in devices seq_file implementation Date: Fri, 19 Aug 2005 14:27:44 +0200 Message-ID: <4305D040.1050301@tu-harburg.de> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------040904050300090802050903" Return-path: Received: from smtp2.rz.tu-harburg.de ([134.28.205.13]:2852 "EHLO smtp2.rz.tu-harburg.de") by vger.kernel.org with ESMTP id S932197AbVHWPRR (ORCPT ); Tue, 23 Aug 2005 11:17:17 -0400 Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org Cc: Andrew Morton , Linux-Kernel Mailing List This is a multi-part message in MIME format. --------------040904050300090802050903 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit I know that scsi procfs is legacy code but this is a fix for a memory leak. While reading through sg.c I realized that the implementation of /proc/scsi/sg/devices with seq_file is leaking memory due to freeing the pointer returned by the next() iterator method. Since next() might return NULL or an error this is wrong. This patch fixes it through using the seq_files private field for holding the reference to the iterator object. Here is a small bash script to trigger the leak. Use slabtop to watch the size-32 usage grow and grow. [--snipp--] #!/bin/sh while true; do cat /proc/scsi/sg/devices > /dev/null done [--snipp--] Signed-off-by: Jan Blunck --------------040904050300090802050903 Content-Type: text/x-patch; name="scsi_sg.c-dev_seq_file-fix.diff" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="scsi_sg.c-dev_seq_file-fix.diff" drivers/scsi/sg.c | 16 +++++++++------- 1 files changed, 9 insertions(+), 7 deletions(-) Index: experimental-jb/drivers/scsi/sg.c =================================================================== --- experimental-jb.orig/drivers/scsi/sg.c +++ experimental-jb/drivers/scsi/sg.c @@ -2971,23 +2971,22 @@ static void * dev_seq_start(struct seq_f { struct sg_proc_deviter * it = kmalloc(sizeof(*it), GFP_KERNEL); + s->private = it; if (! it) return NULL; + if (NULL == sg_dev_arr) - goto err1; + return NULL; it->index = *pos; it->max = sg_last_dev(); if (it->index >= it->max) - goto err1; + return NULL; return it; -err1: - kfree(it); - return NULL; } static void * dev_seq_next(struct seq_file *s, void *v, loff_t *pos) { - struct sg_proc_deviter * it = (struct sg_proc_deviter *) v; + struct sg_proc_deviter * it = s->private; *pos = ++it->index; return (it->index < it->max) ? it : NULL; @@ -2995,7 +2994,10 @@ static void * dev_seq_next(struct seq_fi static void dev_seq_stop(struct seq_file *s, void *v) { - kfree (v); + struct sg_proc_deviter *it = s->private; + + if (it) + kfree (it); } static int sg_proc_open_dev(struct inode *inode, struct file *file) --------------040904050300090802050903--