> On Nov 18, 2020, at 5:19 PM, trondmy@xxxxxxxxxx wrote:
>
> From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
>
> When doing a read() into a page, we also don't care if the nul padding
> stays in that last page when the data length is not 32-bit aligned.
What if the READ payload lands in the middle of a file? The
pad on the end will overwrite file content just past where
the READ payload lands.
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> fs/nfs/nfs2xdr.c | 2 +-
> fs/nfs/nfs3xdr.c | 2 +-
> fs/nfs/nfs4xdr.c | 2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c
> index db9c265ad9e1..468bfbfe44d7 100644
> --- a/fs/nfs/nfs2xdr.c
> +++ b/fs/nfs/nfs2xdr.c
> @@ -102,7 +102,7 @@ static int decode_nfsdata(struct xdr_stream *xdr, struct nfs_pgio_res *result)
> if (unlikely(!p))
> return -EIO;
> count = be32_to_cpup(p);
> - recvd = xdr_read_pages(xdr, count);
> + recvd = xdr_read_pages(xdr, xdr_align_size(count));
> if (unlikely(count > recvd))
> goto out_cheating;
> out:
> diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
> index d3e1726d538b..8ef7c961d3e2 100644
> --- a/fs/nfs/nfs3xdr.c
> +++ b/fs/nfs/nfs3xdr.c
> @@ -1611,7 +1611,7 @@ static int decode_read3resok(struct xdr_stream *xdr,
> ocount = be32_to_cpup(p++);
> if (unlikely(ocount != count))
> goto out_mismatch;
> - recvd = xdr_read_pages(xdr, count);
> + recvd = xdr_read_pages(xdr, xdr_align_size(count));
> if (unlikely(count > recvd))
> goto out_cheating;
> out:
> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> index 755b556e85c3..5baa767106dc 100644
> --- a/fs/nfs/nfs4xdr.c
> +++ b/fs/nfs/nfs4xdr.c
> @@ -5202,7 +5202,7 @@ static int decode_read(struct xdr_stream *xdr, struct rpc_rqst *req,
> return -EIO;
> eof = be32_to_cpup(p++);
> count = be32_to_cpup(p);
> - recvd = xdr_read_pages(xdr, count);
> + recvd = xdr_read_pages(xdr, xdr_align_size(count));
> if (count > recvd) {
> dprintk("NFS: server cheating in read reply: "
> "count %u > recvd %u\n", count, recvd);
> --
> 2.28.0
>
--
Chuck Lever
