nfsd4: enforce rd_dircount
As long as we're here, let's enforce the protocol's limit on the number
of directory entries to return in a readdir.
I don't think anyone's ever noticed our lack of enforcement, but maybe
there's more of a chance they will now that we allow larger readdirs.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 4d79e53..3f2a52c 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1033,7 +1033,7 @@
READ_BUF(24);
READ64(readdir->rd_cookie);
COPYMEM(readdir->rd_verf.data, sizeof(readdir->rd_verf.data));
- READ32(readdir->rd_dircount); /* just in case you needed a useless field... */
+ READ32(readdir->rd_dircount);
READ32(readdir->rd_maxcount);
if ((status = nfsd4_decode_bitmap(argp, readdir->rd_bmval)))
goto out;
@@ -2720,6 +2720,9 @@
if (entry_bytes > cd->rd_maxcount)
goto fail;
cd->rd_maxcount -= entry_bytes;
+ if (!cd->rd_dircount)
+ goto fail;
+ cd->rd_dircount--;
cd->cookie_offset = cookie_offset;
skip_entry:
cd->common.err = nfs_ok;