This is a note to let you know that I've just added the patch titled ext4: don't allow journal inode to have encrypt flag to the 5.10-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-don-t-allow-journal-inode-to-have-encrypt-flag.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 105c78e12468413e426625831faa7db4284e1fec Mon Sep 17 00:00:00 2001 From: Eric Biggers <ebiggers@xxxxxxxxxx> Date: Tue, 1 Nov 2022 22:33:12 -0700 Subject: ext4: don't allow journal inode to have encrypt flag From: Eric Biggers <ebiggers@xxxxxxxxxx> commit 105c78e12468413e426625831faa7db4284e1fec upstream. Mounting a filesystem whose journal inode has the encrypt flag causes a NULL dereference in fscrypt_limit_io_blocks() when the 'inlinecrypt' mount option is used. The problem is that when jbd2_journal_init_inode() calls bmap(), it eventually finds its way into ext4_iomap_begin(), which calls fscrypt_limit_io_blocks(). fscrypt_limit_io_blocks() requires that if the inode is encrypted, then its encryption key must already be set up. That's not the case here, since the journal inode is never "opened" like a normal file would be. Hence the crash. A reproducer is: mkfs.ext4 -F /dev/vdb debugfs -w /dev/vdb -R "set_inode_field <8> flags 0x80808" mount /dev/vdb /mnt -o inlinecrypt To fix this, make ext4 consider journal inodes with the encrypt flag to be invalid. (Note, maybe other flags should be rejected on the journal inode too. For now, this is just the minimal fix for the above issue.) I've marked this as fixing the commit that introduced the call to fscrypt_limit_io_blocks(), since that's what made an actual crash start being possible. But this fix could be applied to any version of ext4 that supports the encrypt feature. Reported-by: syzbot+ba9dac45bc76c490b7c3@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 38ea50daa7a4 ("ext4: support direct I/O with fscrypt using blk-crypto") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> Link: https://lore.kernel.org/r/20221102053312.189962-1-ebiggers@xxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Cc: stable@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5262,7 +5262,7 @@ static struct inode *ext4_get_journal_in jbd_debug(2, "Journal inode found at %p: %lld bytes\n", journal_inode, journal_inode->i_size); - if (!S_ISREG(journal_inode->i_mode)) { + if (!S_ISREG(journal_inode->i_mode) || IS_ENCRYPTED(journal_inode)) { ext4_msg(sb, KERN_ERR, "invalid journal inode"); iput(journal_inode); return NULL; Patches currently in stable-queue which might be from ebiggers@xxxxxxxxxx are queue-5.10/fs-ext4-initialize-fsdata-in-pagecache_write.patch queue-5.10/ext4-fix-leaking-uninitialized-memory-in-fast-commit.patch queue-5.10/ext4-don-t-allow-journal-inode-to-have-encrypt-flag.patch