From 4ea99936a1630f51fc3a2d61a58ec4a1c4b7d55a Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Thu, 7 Nov 2019 21:43:41 -0500 Subject: ext4: add more paranoia checking in ext4_expand_extra_isize handling 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 Cc: stable@kernel.org --- fs/ext4/inode.c | 15 +++++++++++++++ fs/ext4/super.c | 21 ++++++++++++--------- 2 files changed, 27 insertions(+), 9 deletions(-) (limited to 'fs/ext4') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 381813205f99..c6e3fe287b50 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5569,8 +5569,23 @@ static int __ext4_expand_extra_isize(struct inode *inode, { 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); int error; + /* 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); diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 7796e2ffc294..71af8780d4ee 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3545,12 +3545,15 @@ static void ext4_clamp_want_extra_isize(struct super_block *sb) { 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 == 0) { - 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)) @@ -3563,10 +3566,10 @@ static void ext4_clamp_want_extra_isize(struct super_block *sb) } } /* 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"); } -- cgit v1.2.3 From c7df4a1ecb8579838ec8c56b2bb6a6716e974f37 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Mon, 11 Nov 2019 22:18:13 -0500 Subject: ext4: work around deleting a file with i_nlink == 0 safely If the file system is corrupted such that a file's i_links_count is too small, then it's possible that when unlinking that file, i_nlink will already be zero. Previously we were working around this kind of corruption by forcing i_nlink to one; but we were doing this before trying to delete the directory entry --- and if the file system is corrupted enough that ext4_delete_entry() fails, then we exit with i_nlink elevated, and this causes the orphan inode list handling to be FUBAR'ed, such that when we unmount the file system, the orphan inode list can get corrupted. A better way to fix this is to simply skip trying to call drop_nlink() if i_nlink is already zero, thus moving the check to the place where it makes the most sense. https://bugzilla.kernel.org/show_bug.cgi?id=205433 Link: https://lore.kernel.org/r/20191112032903.8828-1-tytso@mit.edu Signed-off-by: Theodore Ts'o Cc: stable@kernel.org Reviewed-by: Andreas Dilger --- fs/ext4/namei.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'fs/ext4') diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index a67cae3c8ff5..a856997d87b5 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -3196,18 +3196,17 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry) if (IS_DIRSYNC(dir)) ext4_handle_sync(handle); - if (inode->i_nlink == 0) { - ext4_warning_inode(inode, "Deleting file '%.*s' with no links", - dentry->d_name.len, dentry->d_name.name); - set_nlink(inode, 1); - } retval = ext4_delete_entry(handle, dir, de, bh); if (retval) goto end_unlink; dir->i_ctime = dir->i_mtime = current_time(dir); ext4_update_dx_flag(dir); ext4_mark_inode_dirty(handle, dir); - drop_nlink(inode); + if (inode->i_nlink == 0) + ext4_warning_inode(inode, "Deleting file '%.*s' with no links", + dentry->d_name.len, dentry->d_name.name); + else + drop_nlink(inode); if (!inode->i_nlink) ext4_orphan_add(handle, inode); inode->i_ctime = current_time(inode); -- cgit v1.2.3