io_uring/zcrx: check unsupported flags on import

[ Upstream commit 7496e65 ]

The imoorted zcrx registration path checks for ZCRX_REG_IMPORT, as it
should, but doesn't reject any unsupported flags. Fix that.

Cc: stable@vger.kernel.org
Fixes: 00d9148 ("io_uring/zcrx: share an ifq between rings")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: isilence

io_uring/zcrx.c

@@ -677,6 +677,8 @@ static int import_zcrx(struct io_ring_ctx *ctx,
 		return -EINVAL;
 	if (reg->if_rxq || reg->rq_entries || reg->area_ptr || reg->region_ptr)
 		return -EINVAL;
+	if (reg->flags & ~ZCRX_REG_IMPORT)
+		return -EINVAL;
 
 	fd = reg->if_idx;
 	CLASS(fd, f)(fd);