diff options
| author | Barret Rhoden <brho@google.com> | 2019-04-25 11:55:50 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-23 08:19:34 +0100 |
| commit | d1c813850f24780eff793bbfbf4e33214ca81e8d (patch) | |
| tree | 63a1ed7f7f797d0dc2f9ee2c6eedfdf7a4d79518 /fs/ext4 | |
| parent | 7c41a8662b6bab58eee8c2e8c6083efd5050f167 (diff) | |
ext4: fix use-after-free race with debug_want_extra_isize
commit 7bc04c5c2cc467c5b40f2b03ba08da174a0d5fa7 upstream.
When remounting with debug_want_extra_isize, we were not performing the
same checks that we do during a normal mount. That allowed us to set a
value for s_want_extra_isize that reached outside the s_inode_size.
Fixes: e2b911c53584 ("ext4: clean up feature test macros with predicate functions")
Reported-by: syzbot+f584efa0ac7213c226b7@syzkaller.appspotmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Barret Rhoden <brho@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[bwh: Backported to 4.9: The debug_want_extra_isize mount option is not
supported]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/super.c | 56 |
1 files changed, 33 insertions, 23 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 3261478bfc32..cea813adbe12 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3342,6 +3342,36 @@ int ext4_calculate_overhead(struct super_block *sb) return 0; } +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; + + /* 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 (ext4_has_feature_extra_isize(sb)) { + if (sbi->s_want_extra_isize < + le16_to_cpu(es->s_want_extra_isize)) + sbi->s_want_extra_isize = + le16_to_cpu(es->s_want_extra_isize); + if (sbi->s_want_extra_isize < + le16_to_cpu(es->s_min_extra_isize)) + sbi->s_want_extra_isize = + le16_to_cpu(es->s_min_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; + ext4_msg(sb, KERN_INFO, + "required extra inode space not available"); + } +} + static void ext4_set_resv_clusters(struct super_block *sb) { ext4_fsblk_t resv_clusters; @@ -4156,29 +4186,7 @@ no_journal: if (ext4_setup_super(sb, es, sb->s_flags & MS_RDONLY)) sb->s_flags |= MS_RDONLY; - /* 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 (ext4_has_feature_extra_isize(sb)) { - if (sbi->s_want_extra_isize < - le16_to_cpu(es->s_want_extra_isize)) - sbi->s_want_extra_isize = - le16_to_cpu(es->s_want_extra_isize); - if (sbi->s_want_extra_isize < - le16_to_cpu(es->s_min_extra_isize)) - sbi->s_want_extra_isize = - le16_to_cpu(es->s_min_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; - ext4_msg(sb, KERN_INFO, "required extra inode space not" - "available"); - } + ext4_clamp_want_extra_isize(sb); ext4_set_resv_clusters(sb); @@ -4959,6 +4967,8 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data) goto restore_opts; } + ext4_clamp_want_extra_isize(sb); + if ((old_opts.s_mount_opt & EXT4_MOUNT_JOURNAL_CHECKSUM) ^ test_opt(sb, JOURNAL_CHECKSUM)) { ext4_msg(sb, KERN_ERR, "changing journal_checksum " |