On Wed 31-01-24 20:04:27, Edward Adam Davis wrote:
> Before reusing the handle, it is necessary to confirm that the transaction is
> ready.
>
> Reported-and-tested-by: syzbot+cdee56dbcdf0096ef605@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
Sorry but no. Dave found a way to fix this particular problem in XFS and
your patch would not really improve anything because we'd just crash
when dereferencing handle->saved_alloc_context.
Honza
> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
> index cb0b8d6fc0c6..702312cd5392 100644
> --- a/fs/jbd2/transaction.c
> +++ b/fs/jbd2/transaction.c
> @@ -493,6 +493,9 @@ handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
> return ERR_PTR(-EROFS);
>
> if (handle) {
> + if (handle->saved_alloc_context & ~PF_MEMALLOC_NOFS)
> + return ERR_PTR(-EBUSY);
> +
> J_ASSERT(handle->h_transaction->t_journal == journal);
> handle->h_ref++;
> return handle;
> --
> 2.43.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
