From 78d0d2063bab954d19a1696feae4c7706a626d48 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 19 Jun 2023 09:41:05 -0600 Subject: [PATCH] io_uring/net: disable partial retries for recvmsg with cmsg We cannot sanely handle partial retries for recvmsg if we have cmsg attached. If we don't, then we'd just be overwriting the initial cmsg header on retries. Alternatively we could increment and handle this appropriately, but it doesn't seem worth the complication. Move the MSG_WAITALL check into the non-multishot case while at it, since MSG_WAITALL is explicitly disabled for multishot anyway. Link: https://lore.kernel.org/io-uring/0b0d4411-c8fd-4272-770b-e030af6919a0@kernel.dk/ Cc: stable@vger.kernel.org # 5.10+ Reported-by: Stefan Metzmacher Reviewed-by: Stefan Metzmacher Signed-off-by: Jens Axboe --- io_uring/net.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/io_uring/net.c b/io_uring/net.c index c0924ab1ea11..2bc2cb2f4d6c 100644 --- a/io_uring/net.c +++ b/io_uring/net.c @@ -789,16 +789,19 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags) flags = sr->msg_flags; if (force_nonblock) flags |= MSG_DONTWAIT; - if (flags & MSG_WAITALL) - min_ret = iov_iter_count(&kmsg->msg.msg_iter); kmsg->msg.msg_get_inq = 1; - if (req->flags & REQ_F_APOLL_MULTISHOT) + if (req->flags & REQ_F_APOLL_MULTISHOT) { ret = io_recvmsg_multishot(sock, sr, kmsg, flags, &mshot_finished); - else + } else { + /* disable partial retry for recvmsg with cmsg attached */ + if (flags & MSG_WAITALL && !kmsg->msg.msg_controllen) + min_ret = iov_iter_count(&kmsg->msg.msg_iter); + ret = __sys_recvmsg_sock(sock, &kmsg->msg, sr->umsg, kmsg->uaddr, flags); + } if (ret < min_ret) { if (ret == -EAGAIN && force_nonblock) {