On Thu, 2020-11-19 at 09:17 -0500, Chuck Lever wrote:
>
>
> > 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.
If the size > buf->page_len, then it gets truncated in
xdr_align_pages() afaik.
>
>
> > 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
>
>
>
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
