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Revision 9aea5a65aa7a1af9a4236dfaeb0088f1624f9919 authored by Roland McGrath on 08 September 2010, 02:37:06 UTC, committed by Linus Torvalds on 10 September 2010, 15:10:26 UTC 
execve: make responsive to SIGKILL with large arguments
 
An execve with a very large total of argument/environment strings
can take a really long time in the execve system call.  It runs
uninterruptibly to count and copy all the strings.  This change
makes it abort the exec quickly if sent a SIGKILL.

Note that this is the conservative change, to interrupt only for
SIGKILL, by using fatal_signal_pending().  It would be perfectly
correct semantics to let any signal interrupt the string-copying in
execve, i.e. use signal_pending() instead of fatal_signal_pending().
We'll save that change for later, since it could have user-visible
consequences, such as having a timer set too quickly make it so that
an execve can never complete, though it always happened to work before.

Signed-off-by: Roland McGrath <roland@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 7993bc1
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internal.h 
/* fs/ internal definitions
 *
 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/lglock.h>

struct super_block;
struct linux_binprm;
struct path;

/*
 * block_dev.c
 */
#ifdef CONFIG_BLOCK
extern struct super_block *blockdev_superblock;
extern void __init bdev_cache_init(void);

static inline int sb_is_blkdev_sb(struct super_block *sb)
{
	return sb == blockdev_superblock;
}

extern int __sync_blockdev(struct block_device *bdev, int wait);

#else
static inline void bdev_cache_init(void)
{
}

static inline int sb_is_blkdev_sb(struct super_block *sb)
{
	return 0;
}

static inline int __sync_blockdev(struct block_device *bdev, int wait)
{
	return 0;
}
#endif

/*
 * char_dev.c
 */
extern void __init chrdev_init(void);

/*
 * exec.c
 */
extern int check_unsafe_exec(struct linux_binprm *);

/*
 * namespace.c
 */
extern int copy_mount_options(const void __user *, unsigned long *);
extern int copy_mount_string(const void __user *, char **);

extern void free_vfsmnt(struct vfsmount *);
extern struct vfsmount *alloc_vfsmnt(const char *);
extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
extern void mnt_set_mountpoint(struct vfsmount *, struct dentry *,
				struct vfsmount *);
extern void release_mounts(struct list_head *);
extern void umount_tree(struct vfsmount *, int, struct list_head *);
extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int);

extern void __init mnt_init(void);

DECLARE_BRLOCK(vfsmount_lock);


/*
 * fs_struct.c
 */
extern void chroot_fs_refs(struct path *, struct path *);

/*
 * file_table.c
 */
extern void file_sb_list_add(struct file *f, struct super_block *sb);
extern void file_sb_list_del(struct file *f);
extern void mark_files_ro(struct super_block *);
extern struct file *get_empty_filp(void);

/*
 * super.c
 */
extern int do_remount_sb(struct super_block *, int, void *, int);
extern void __put_super(struct super_block *sb);
extern void put_super(struct super_block *sb);

/*
 * open.c
 */
struct nameidata;
extern struct file *nameidata_to_filp(struct nameidata *);
extern void release_open_intent(struct nameidata *);
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