From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wright Subject: [PATCH 6/7] [PATCH] sg.c: fix a memory leak in devices seq_file implementation (2nd) Date: Fri, 26 Aug 2005 12:18:01 -0700 Message-ID: <20050826191942.444423000@localhost.localdomain> References: <20050826191755.052951000@localhost.localdomain> Return-path: Content-Disposition: inline; filename=fix-memory-leak-in-sg.c-seq_file.patch Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, stable@kernel.org, Ingo Oeser Cc: Justin Forbes , Zwane Mwaikambo , Theodore Ts'o , Randy Dunlap , Chuck Wolber , torvalds@osdl.org, akpm@osdl.org, alan@lxorguk.ukuu.org.uk, linux-scsi@vger.kernel.org, Jan Blunck , Chris Wright List-Id: linux-scsi@vger.kernel.org -stable review patch. If anyone has any objections, please let us know. ------------------ 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. #!/bin/sh while true; do cat /proc/scsi/sg/devices > /dev/null done Signed-off-by: Jan Blunck Signed-off-by: Chris Wright --- drivers/scsi/sg.c | 15 ++++++++------- 1 files changed, 8 insertions(+), 7 deletions(-) Index: linux-2.6.12.y/drivers/scsi/sg.c =================================================================== --- linux-2.6.12.y.orig/drivers/scsi/sg.c +++ linux-2.6.12.y/drivers/scsi/sg.c @@ -2969,23 +2969,22 @@ 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; @@ -2993,7 +2992,9 @@ 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; + + kfree (it); } static int sg_proc_open_dev(struct inode *inode, struct file *file) --