io_recvmsg() takes the transfer length from the ring provided buffer when sqe->len is 0, and such a buffer can be up to 4G. min_ret is an int, so 2G or more makes it negative and the (ret < min_ret) block is skipped, and the oversized length reaches the socket layer unchanged: an empty socket then completes with 0 instead of arming poll, and a short read is reported as complete. Clamp the length to MAX_RW_COUNT, as io_recv() does. Fixes: 78d0d2063bab ("io_uring/net: disable partial retries for recvmsg with cmsg") Signed-off-by: Yichong Chen --- io_uring/net.c | 1 + 1 file changed, 1 insertion(+) diff --git a/io_uring/net.c b/io_uring/net.c index eeab88e77fd8..4678f29f5177 100644 --- a/io_uring/net.c +++ b/io_uring/net.c @@ -1068,6 +1068,7 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags) sel = io_buffer_select(req, &len, sr->buf_group, issue_flags); if (!sel.addr) return -ENOBUFS; + len = min_t(size_t, len, MAX_RW_COUNT); if (req->flags & REQ_F_APOLL_MULTISHOT) { ret = io_recvmsg_prep_multishot(kmsg, sr, &sel.addr, &len); -- 2.51.0