From: Jens Axboe axboe@kernel.dk
commit 78d0d2063bab954d19a1696feae4c7706a626d48 upstream.
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... Cc: stable@vger.kernel.org # 5.10+ Reported-by: Stefan Metzmacher metze@samba.org Reviewed-by: Stefan Metzmacher metze@samba.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/net.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/io_uring/net.c +++ b/io_uring/net.c @@ -789,16 +789,19 @@ retry_multishot: 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) {