6.5-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
commit f8f9ab2d98116e79d220f1d089df7464ad4e026d upstream.
io_uring does non-blocking connection attempts, which can yield some unexpected results if a connect request is re-attempted by an an application. This is equivalent to the following sync syscall sequence:
sock = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP); connect(sock, &addr, sizeof(addr);
ret == -1 and errno == EINPROGRESS expected here. Now poll for POLLOUT on sock, and when that returns, we expect the socket to be connected. But if we follow that procedure with:
connect(sock, &addr, sizeof(addr));
you'd expect ret == -1 and errno == EISCONN here, but you actually get ret == 0. If we attempt the connection one more time, then we get EISCON as expected.
io_uring used to do this, but turns out that bluetooth fails with EBADFD if you attempt to re-connect. Also looks like EISCONN _could_ occur with this sequence.
Retain the ->in_progress logic, but work-around a potential EISCONN or EBADFD error and only in those cases look at the sock_error(). This should work in general and avoid the odd sequence of a repeated connect request returning success when the socket is already connected.
This is all a side effect of the socket state being in a CONNECTING state when we get EINPROGRESS, and only a re-connect or other related operation will turn that into CONNECTED.
Cc: stable@vger.kernel.org Fixes: 3fb1bd688172 ("io_uring/net: handle -EINPROGRESS correct for IORING_OP_CONNECT") Link: https://github.com/axboe/liburing/issues/980 Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/net.c | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-)
--- a/io_uring/net.c +++ b/io_uring/net.c @@ -1461,16 +1461,6 @@ int io_connect(struct io_kiocb *req, uns int ret; bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
- if (connect->in_progress) { - struct socket *socket; - - ret = -ENOTSOCK; - socket = sock_from_file(req->file); - if (socket) - ret = sock_error(socket->sk); - goto out; - } - if (req_has_async_data(req)) { io = req->async_data; } else { @@ -1490,9 +1480,7 @@ int io_connect(struct io_kiocb *req, uns && force_nonblock) { if (ret == -EINPROGRESS) { connect->in_progress = true; - return -EAGAIN; - } - if (ret == -ECONNABORTED) { + } else if (ret == -ECONNABORTED) { if (connect->seen_econnaborted) goto out; connect->seen_econnaborted = true; @@ -1506,6 +1494,16 @@ int io_connect(struct io_kiocb *req, uns memcpy(req->async_data, &__io, sizeof(__io)); return -EAGAIN; } + if (connect->in_progress) { + /* + * At least bluetooth will return -EBADFD on a re-connect + * attempt, and it's (supposedly) also valid to get -EISCONN + * which means the previous result is good. For both of these, + * grab the sock_error() and use that for the completion. + */ + if (ret == -EBADFD || ret == -EISCONN) + ret = sock_error(sock_from_file(req->file)->sk); + } if (ret == -ERESTARTSYS) ret = -EINTR; out: