mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-25 21:54:06 +08:00
1f55c718c2
Considering current pty code and multiple devpts instances, it's possible to umount a devpts file system while a program still has /dev/tty opened pointing to a previosuly closed pty pair in that instance. In the case all ptmx and pts/N files are closed, umount can be done. If the program closes /dev/tty after umount is done, devpts_kill_index will use now an invalid super_block, which was already destroyed in the umount operation after running ->kill_sb. This is another "use after free" type of issue, but now related to the allocated super_block instance. To avoid the problem (warning at ida_remove and potential crashes) for this specific case, I added two functions in devpts which grabs additional references to the super_block, which pty code now uses so it makes sure the super block structure is still valid until pty shutdown is done. I also moved the additional inode references to the same functions, which also covered similar case with inode being freed before /dev/tty final close/shutdown. Signed-off-by: Herton R. Krzesinski <herton@redhat.com> Cc: stable@vger.kernel.org # 2.6.29+ Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
54 lines
1.6 KiB
C
54 lines
1.6 KiB
C
/* -*- linux-c -*- --------------------------------------------------------- *
|
|
*
|
|
* linux/include/linux/devpts_fs.h
|
|
*
|
|
* Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
|
|
*
|
|
* This file is part of the Linux kernel and is made available under
|
|
* the terms of the GNU General Public License, version 2, or at your
|
|
* option, any later version, incorporated herein by reference.
|
|
*
|
|
* ------------------------------------------------------------------------- */
|
|
|
|
#ifndef _LINUX_DEVPTS_FS_H
|
|
#define _LINUX_DEVPTS_FS_H
|
|
|
|
#include <linux/errno.h>
|
|
|
|
#ifdef CONFIG_UNIX98_PTYS
|
|
|
|
int devpts_new_index(struct inode *ptmx_inode);
|
|
void devpts_kill_index(struct inode *ptmx_inode, int idx);
|
|
void devpts_add_ref(struct inode *ptmx_inode);
|
|
void devpts_del_ref(struct inode *ptmx_inode);
|
|
/* mknod in devpts */
|
|
struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index,
|
|
void *priv);
|
|
/* get private structure */
|
|
void *devpts_get_priv(struct inode *pts_inode);
|
|
/* unlink */
|
|
void devpts_pty_kill(struct inode *inode);
|
|
|
|
#else
|
|
|
|
/* Dummy stubs in the no-pty case */
|
|
static inline int devpts_new_index(struct inode *ptmx_inode) { return -EINVAL; }
|
|
static inline void devpts_kill_index(struct inode *ptmx_inode, int idx) { }
|
|
static inline void devpts_add_ref(struct inode *ptmx_inode) { }
|
|
static inline void devpts_del_ref(struct inode *ptmx_inode) { }
|
|
static inline struct inode *devpts_pty_new(struct inode *ptmx_inode,
|
|
dev_t device, int index, void *priv)
|
|
{
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
static inline void *devpts_get_priv(struct inode *pts_inode)
|
|
{
|
|
return NULL;
|
|
}
|
|
static inline void devpts_pty_kill(struct inode *inode) { }
|
|
|
|
#endif
|
|
|
|
|
|
#endif /* _LINUX_DEVPTS_FS_H */
|