> On Sep 30, 2021, at 3:44 PM, trondmy@xxxxxxxxxx wrote:
>
> From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
>
> RFC3530 notes that the 'dircount' field may be zero, in which case the
> recommendation is to ignore it, and only enforce the 'maxcount' field.
> In RFC5661, this recommendation to ignore a zero valued field becomes a
> requirement.
>
> Fixes: aee377644146 ("nfsd4: fix rd_dircount enforcement")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Pulled into the next 5.15-rc for NFSD. Thanks!
> ---
> fs/nfsd/nfs4xdr.c | 19 +++++++++++--------
> 1 file changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 7abeccb975b2..cf030ebe2827 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -3544,15 +3544,18 @@ nfsd4_encode_dirent(void *ccdv, const char *name, int namlen,
> goto fail;
> cd->rd_maxcount -= entry_bytes;
> /*
> - * RFC 3530 14.2.24 describes rd_dircount as only a "hint", so
> - * let's always let through the first entry, at least:
> + * RFC 3530 14.2.24 describes rd_dircount as only a "hint", and
> + * notes that it could be zero. If it is zero, then the server
> + * should enforce only the rd_maxcount value.
> */
> - if (!cd->rd_dircount)
> - goto fail;
> - name_and_cookie = 4 + 4 * XDR_QUADLEN(namlen) + 8;
> - if (name_and_cookie > cd->rd_dircount && cd->cookie_offset)
> - goto fail;
> - cd->rd_dircount -= min(cd->rd_dircount, name_and_cookie);
> + if (cd->rd_dircount) {
> + name_and_cookie = 4 + 4 * XDR_QUADLEN(namlen) + 8;
> + if (name_and_cookie > cd->rd_dircount && cd->cookie_offset)
> + goto fail;
> + cd->rd_dircount -= min(cd->rd_dircount, name_and_cookie);
> + if (!cd->rd_dircount)
> + cd->rd_maxcount = 0;
> + }
>
> cd->cookie_offset = cookie_offset;
> skip_entry:
> --
> 2.31.1
>
--
Chuck Lever
