This is a note to let you know that I've just added the patch titled ext4: update s_journal_inum if it changes after journal replay to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ext4-update-s_journal_inum-if-it-changes-after-journ.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 01341a6e3e36b3635c2093c56a888aaa0ac7f63e Author: Baokun Li <libaokun1@xxxxxxxxxx> Date: Sat Jan 7 11:21:26 2023 +0800 ext4: update s_journal_inum if it changes after journal replay [ Upstream commit 3039d8b8692408438a618fac2776b629852663c3 ] 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@xxxxxxx> Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Link: https://lore.kernel.org/r/20230107032126.4165860-3-libaokun1@xxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 802ca160d31ed..6df4da084190f 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5385,8 +5385,11 @@ 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); }