From: Theodore Ts'o tytso@mit.edu
commit 4ea99936a1630f51fc3a2d61a58ec4a1c4b7d55a upstream.
It's possible to specify a non-zero s_want_extra_isize via debugging option, and this can cause bad things(tm) to happen when using a file system with an inode size of 128 bytes.
Add better checking when the file system is mounted, as well as when we are actually doing the trying to do the inode expansion.
Link: https://lore.kernel.org/r/20191110121510.GH23325@mit.edu Reported-by: syzbot+f8d6f8386ceacdbfff57@syzkaller.appspotmail.com Reported-by: syzbot+33d7ea72e47de3bdf4e1@syzkaller.appspotmail.com Reported-by: syzbot+44b6763edfc17144296f@syzkaller.appspotmail.com Signed-off-by: Theodore Ts'o tytso@mit.edu [bwh: Backported to 4.4: adjust context] Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/inode.c | 15 +++++++++++++++ fs/ext4/super.c | 20 ++++++++++++-------- 2 files changed, 27 insertions(+), 8 deletions(-)
--- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5189,10 +5189,25 @@ static int ext4_expand_extra_isize(struc { struct ext4_inode *raw_inode; struct ext4_xattr_ibody_header *header; + unsigned int inode_size = EXT4_INODE_SIZE(inode->i_sb); + struct ext4_inode_info *ei = EXT4_I(inode);
if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) return 0;
+ /* this was checked at iget time, but double check for good measure */ + if ((EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize > inode_size) || + (ei->i_extra_isize & 3)) { + EXT4_ERROR_INODE(inode, "bad extra_isize %u (inode size %u)", + ei->i_extra_isize, + EXT4_INODE_SIZE(inode->i_sb)); + return -EFSCORRUPTED; + } + if ((new_extra_isize < ei->i_extra_isize) || + (new_extra_isize < 4) || + (new_extra_isize > inode_size - EXT4_GOOD_OLD_INODE_SIZE)) + return -EINVAL; /* Should never happen */ + raw_inode = ext4_raw_inode(&iloc);
header = IHDR(inode, raw_inode); --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3173,11 +3173,15 @@ static void ext4_clamp_want_extra_isize( { struct ext4_sb_info *sbi = EXT4_SB(sb); struct ext4_super_block *es = sbi->s_es; + unsigned def_extra_isize = sizeof(struct ext4_inode) - + EXT4_GOOD_OLD_INODE_SIZE;
- /* determine the minimum size of new large inodes, if present */ - if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE) { - sbi->s_want_extra_isize = sizeof(struct ext4_inode) - - EXT4_GOOD_OLD_INODE_SIZE; + if (sbi->s_inode_size == EXT4_GOOD_OLD_INODE_SIZE) { + sbi->s_want_extra_isize = 0; + return; + } + if (sbi->s_want_extra_isize < 4) { + sbi->s_want_extra_isize = def_extra_isize; if (ext4_has_feature_extra_isize(sb)) { if (sbi->s_want_extra_isize < le16_to_cpu(es->s_want_extra_isize)) @@ -3190,10 +3194,10 @@ static void ext4_clamp_want_extra_isize( } } /* Check if enough inode space is available */ - if (EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize > - sbi->s_inode_size) { - sbi->s_want_extra_isize = sizeof(struct ext4_inode) - - EXT4_GOOD_OLD_INODE_SIZE; + if ((sbi->s_want_extra_isize > sbi->s_inode_size) || + (EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize > + sbi->s_inode_size)) { + sbi->s_want_extra_isize = def_extra_isize; ext4_msg(sb, KERN_INFO, "required extra inode space not available"); }