nfsd4: fix rd_dircount enforcement
Commit 3b299709091b "nfsd4: enforce rd_dircount" totally misunderstood
rd_dircount; it refers to total non-attribute bytes returned, not number
of directory entries returned.
Bring the code into agreement with RFC 3530 section 14.2.24.
Cc: stable@vger.kernel.org
Fixes: 3b299709091b "nfsd4: enforce rd_dircount"
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index f9821ce..e94457c 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2657,6 +2657,7 @@
struct xdr_stream *xdr = cd->xdr;
int start_offset = xdr->buf->len;
int cookie_offset;
+ u32 name_and_cookie;
int entry_bytes;
__be32 nfserr = nfserr_toosmall;
__be64 wire_offset;
@@ -2718,7 +2719,14 @@
cd->rd_maxcount -= entry_bytes;
if (!cd->rd_dircount)
goto fail;
- cd->rd_dircount--;
+ /*
+ * RFC 3530 14.2.24 describes rd_dircount as only a "hint", so
+ * let's always let through the first entry, at least:
+ */
+ name_and_cookie = 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);
cd->cookie_offset = cookie_offset;
skip_entry:
cd->common.err = nfs_ok;
@@ -3321,6 +3329,10 @@
}
maxcount = min_t(int, maxcount-16, bytes_left);
+ /* RFC 3530 14.2.24 allows us to ignore dircount when it's 0: */
+ if (!readdir->rd_dircount)
+ readdir->rd_dircount = INT_MAX;
+
readdir->xdr = xdr;
readdir->rd_maxcount = maxcount;
readdir->common.err = 0;