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autofs: fix autofs_sbi() does not check super block type

commit 0633da48f0 upstream.

autofs_sbi() does not check the superblock magic number to verify it has
been given an autofs super block.

Backport Note: autofs4 has been renamed to autofs upstream. As a result
the upstream patch does not apply cleanly onto 4.14.y.

Link: http://lkml.kernel.org/r/153475422934.17131.7563724552005298277.stgit@pluto.themaw.net
Reported-by: <syzbot+87c3c541582e56943277@syzkaller.appspotmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Zubin Mithra <zsm@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Ian Kent 2018-08-21 21:51:45 -07:00 committed by Greg Kroah-Hartman
parent daf0ca743b
commit 8b34a7b14e
2 changed files with 3 additions and 2 deletions

View File

@ -26,6 +26,7 @@
#include <linux/list.h>
#include <linux/completion.h>
#include <asm/current.h>
#include <linux/magic.h>
/* This is the range of ioctl() numbers we claim as ours */
#define AUTOFS_IOC_FIRST AUTOFS_IOC_READY
@ -124,7 +125,8 @@ struct autofs_sb_info {
static inline struct autofs_sb_info *autofs4_sbi(struct super_block *sb)
{
return (struct autofs_sb_info *)(sb->s_fs_info);
return sb->s_magic != AUTOFS_SUPER_MAGIC ?
NULL : (struct autofs_sb_info *)(sb->s_fs_info);
}
static inline struct autofs_info *autofs4_dentry_ino(struct dentry *dentry)

View File

@ -14,7 +14,6 @@
#include <linux/pagemap.h>
#include <linux/parser.h>
#include <linux/bitops.h>
#include <linux/magic.h>
#include "autofs_i.h"
#include <linux/module.h>