On Wed, 2020-08-05 at 12:23 -0500, Jeffrey Mitchell wrote:
> Move the buffer size check to decode_attr_security_label() before
> memcpy()
> Only call memcpy() if the buffer is large enough
>
> Signed-off-by: Jeffrey Mitchell <jeffrey.mitchell@xxxxxxxxxx>
> ---
> fs/nfs/nfs4proc.c | 2 --
> fs/nfs/nfs4xdr.c | 5 ++++-
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 2e2dac29a9e9..45e0585e0667 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -5845,8 +5845,6 @@ static int _nfs4_get_security_label(struct
> inode *inode, void *buf,
> return ret;
> if (!(fattr.valid & NFS_ATTR_FATTR_V4_SECURITY_LABEL))
> return -ENOENT;
> - if (buflen < label.len)
> - return -ERANGE;
> return 0;
> }
>
> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> index 47817ef0aadb..50162e0a959c 100644
> --- a/fs/nfs/nfs4xdr.c
> +++ b/fs/nfs/nfs4xdr.c
> @@ -4166,7 +4166,10 @@ static int decode_attr_security_label(struct
> xdr_stream *xdr, uint32_t *bitmap,
> return -EIO;
> if (len < NFS4_MAXLABELLEN) {
> if (label) {
> - memcpy(label->label, p, len);
> + if (label->len && label->len < len)
> + return -ERANGE;
> + if (label->len)
> + memcpy(label->label, p, len);
Just a heads up that I fixed this to avoid the duplicate test of label-
>len != 0 and I added a Fixes: before applying.
> label->len = len;
> label->pi = pi;
> label->lfs = lfs;
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
