Fix Syzbot bug: kernel BUG in ntfs_lookup_inode_by_name https://syzkaller.appspot.com/bug?id=32cf53b48c1846ffc25a185a2e92e170d1a95d71 Check whether $Extend is a directory or not( for NTFS3.0+) while loading system files. If it isn't(as in the case of this bug where the mft record for $Extend contains a regular file), load_system_files() returns false. Reported-by: syzbot+30b7f850c6d98ea461d2@xxxxxxxxxxxxxxxxxxxxxxxxx CC: stable@xxxxxxxxxxxxxxx # 4.9+ Signed-off-by: Soumya Negi <soumya.negi97@xxxxxxxxx> --- Changes since v1: * Added CC tag for stable * Formatted changelog to fit within 72 cols --- fs/ntfs/super.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c index 5ae8de09b271..18e2902531f9 100644 --- a/fs/ntfs/super.c +++ b/fs/ntfs/super.c @@ -2092,10 +2092,15 @@ static bool load_system_files(ntfs_volume *vol) // TODO: Initialize security. /* Get the extended system files' directory inode. */ vol->extend_ino = ntfs_iget(sb, FILE_Extend); - if (IS_ERR(vol->extend_ino) || is_bad_inode(vol->extend_ino)) { + if (IS_ERR(vol->extend_ino) || is_bad_inode(vol->extend_ino) || + !S_ISDIR(vol->extend_ino->i_mode)) { + static const char *es1 = "$Extend is not a directory"; + static const char *es2 = "Failed to load $Extend"; + const char *es = !S_ISDIR(vol->extend_ino->i_mode) ? es1 : es2; + if (!IS_ERR(vol->extend_ino)) iput(vol->extend_ino); - ntfs_error(sb, "Failed to load $Extend."); + ntfs_error(sb, "%s.", es); goto iput_sec_err_out; } #ifdef NTFS_RW -- 2.17.1
