| Message ID | 20230106104706.2410740-3-libaokun1@huawei.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ext4: fix possible null pointer dereference in ext4_get_group_info | expand |
On Fri 06-01-23 18:47:06, Baokun Li wrote: > 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> > --- > fs/ext4/super.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) Looks good. Feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 260c1b3e3ef2..3fe9dc19ff9c 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -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); > } > > -- > 2.31.1 >
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 260c1b3e3ef2..3fe9dc19ff9c 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -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); }
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> --- fs/ext4/super.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)