On Wed, May 04, 2022 at 08:17:19AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> When we first allocate or resize an inline inode fork, we round up
> the allocation to 4 byte alingment to make journal alignment
> constraints. We don't clear the unused bytes, so we can copy up to
> three uninitialised bytes into the journal. Zero those bytes so we
> only ever copy zeros into the journal.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Yup. Thanks for the cleanup.
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> ---
> fs/xfs/libxfs/xfs_inode_fork.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index 9aee4a1e2fe9..a15ff38c3d41 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -50,8 +50,13 @@ xfs_init_local_fork(
> mem_size++;
>
> if (size) {
> + /*
> + * As we round up the allocation here, we need to ensure the
> + * bytes we don't copy data into are zeroed because the log
> + * vectors still copy them into the journal.
> + */
> real_size = roundup(mem_size, 4);
> - ifp->if_u1.if_data = kmem_alloc(real_size, KM_NOFS);
> + ifp->if_u1.if_data = kmem_zalloc(real_size, KM_NOFS);
> memcpy(ifp->if_u1.if_data, data, size);
> if (zero_terminate)
> ifp->if_u1.if_data[size] = '\0';
> @@ -500,10 +505,11 @@ xfs_idata_realloc(
> /*
> * For inline data, the underlying buffer must be a multiple of 4 bytes
> * in size so that it can be logged and stay on word boundaries.
> - * We enforce that here.
> + * We enforce that here, and use __GFP_ZERO to ensure that size
> + * extensions always zero the unused roundup area.
> */
> ifp->if_u1.if_data = krealloc(ifp->if_u1.if_data, roundup(new_size, 4),
> - GFP_NOFS | __GFP_NOFAIL);
> + GFP_NOFS | __GFP_NOFAIL | __GFP_ZERO);
> ifp->if_bytes = new_size;
> }
>
> --
> 2.35.1
>
