4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Ian Kent <ra...@themaw.net> commit 0633da48f0793aeba27f82d30605624416723a91 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.st...@pluto.themaw.net Reported-by: <syzbot+87c3c541582e56943...@syzkaller.appspotmail.com> Signed-off-by: Ian Kent <ra...@themaw.net> Reviewed-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Zubin Mithra <z...@chromium.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- fs/autofs4/autofs_i.h | 4 +++- fs/autofs4/inode.c | 1 - 2 files changed, 3 insertions(+), 2 deletions(-) --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -18,6 +18,7 @@ #include <linux/mutex.h> #include <linux/spinlock.h> #include <linux/list.h> +#include <linux/magic.h> /* This is the range of ioctl() numbers we claim as ours */ #define AUTOFS_IOC_FIRST AUTOFS_IOC_READY @@ -135,7 +136,8 @@ 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) --- a/fs/autofs4/inode.c +++ b/fs/autofs4/inode.c @@ -18,7 +18,6 @@ #include <linux/pagemap.h> #include <linux/parser.h> #include <linux/bitops.h> -#include <linux/magic.h> #include "autofs_i.h" #include <linux/module.h>
