6.1-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
commit a37ee9e117ef73bbc2f5c0b31911afd52d229861 upstream.
If we hit CQ ring overflow when attempting to post a multishot accept completion, we don't properly save the result or return code. This results in losing the accepted fd value.
Instead, we return the result from the poll operation that triggered the accept retry. This is generally POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND which is 0xc3, or 195, which looks like a valid file descriptor, but it really has no connection to that.
Handle this like we do for other multishot completions - assign the result, and return IOU_STOP_MULTISHOT to cancel any further completions from this request when overflow is hit. This preserves the result, as we should, and tells the application that the request needs to be re-armed.
Cc: stable@vger.kernel.org Fixes: 515e26961295 ("io_uring: revert "io_uring fix multishot accept ordering"") Link: https://github.com/axboe/liburing/issues/1062 Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/net.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/io_uring/net.c +++ b/io_uring/net.c @@ -1326,7 +1326,7 @@ retry: * has already been done */ if (issue_flags & IO_URING_F_MULTISHOT) - ret = IOU_ISSUE_SKIP_COMPLETE; + return IOU_ISSUE_SKIP_COMPLETE; return ret; } if (ret == -ERESTARTSYS) @@ -1350,7 +1350,8 @@ retry: if (io_post_aux_cqe(ctx, req->cqe.user_data, ret, IORING_CQE_F_MORE, false)) goto retry;
- return -ECANCELED; + io_req_set_res(req, ret, 0); + return IOU_STOP_MULTISHOT; }
int io_socket_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)