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ext4: update s_journal_inum if it changes after journal replay 

When mounting a crafted ext4 image, s_journal_inum may change after journal
replay, which is obviously unreasonable because we have successfully loaded
and replayed the journal through the old s_journal_inum. And the new
s_journal_inum bypasses some of the checks in ext4_get_journal(), which
may trigger a null pointer dereference problem. So if s_journal_inum
changes after the journal replay, we ignore the change, and rewrite the
current journal_inum to the superblock.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216541
Reported-by: Luís Henriques <lhenriques@suse.de>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230107032126.4165860-3-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Baokun Li 2023-01-07 11:21:26 +08:00 committed by Theodore Ts'o
parent 5cd740287a
commit 3039d8b869
1 changed files with 5 additions and 2 deletions
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7
fs/ext4/super.c
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@ -5953,8 +5953,11 @@ static int ext4_load_journal(struct super_block *sb,
if (!really_read_only && journal_devnum &&
journal_devnum != le32_to_cpu(es->s_journal_dev)) {
es->s_journal_dev = cpu_to_le32(journal_devnum);
/* Make sure we flush the recovery flag to disk. */
ext4_commit_super(sb);
}
if (!really_read_only && journal_inum &&
journal_inum != le32_to_cpu(es->s_journal_inum)) {
es->s_journal_inum = cpu_to_le32(journal_inum);
ext4_commit_super(sb);
}