The patch below does not apply to the 5.5-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d876836204897b6d7d911f942084f69a1e9d5c4d Mon Sep 17 00:00:00 2001

From: Jens Axboe axboe@kernel.dk Date: Thu, 27 Feb 2020 14:17:49 -0700 Subject: [PATCH] io_uring: fix 32-bit compatability with sendmsg/recvmsg

We must set MSG_CMSG_COMPAT if we're in compatability mode, otherwise the iovec import for these commands will not do the right thing and fail the command with -EINVAL.

Found by running the test suite compiled as 32-bit.

Cc: stable@vger.kernel.org Fixes: aa1fa28fc73e ("io_uring: add support for recvmsg()") Fixes: 0fa03c624d8f ("io_uring: add support for sendmsg()") Signed-off-by: Jens Axboe axboe@kernel.dk

diff --git a/fs/io_uring.c b/fs/io_uring.c index 05eea06f5421..6a595c13e108 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3001,6 +3001,11 @@ static int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) sr->msg = u64_to_user_ptr(READ_ONCE(sqe->addr)); sr->len = READ_ONCE(sqe->len);

+#ifdef CONFIG_COMPAT + if (req->ctx->compat) + sr->msg_flags |= MSG_CMSG_COMPAT; +#endif + if (!io || req->opcode == IORING_OP_SEND) return 0; /* iovec is already imported */ @@ -3153,6 +3158,11 @@ static int io_recvmsg_prep(struct io_kiocb *req, sr->msg = u64_to_user_ptr(READ_ONCE(sqe->addr)); sr->len = READ_ONCE(sqe->len);

+#ifdef CONFIG_COMPAT + if (req->ctx->compat) + sr->msg_flags |= MSG_CMSG_COMPAT; +#endif + if (!io || req->opcode == IORING_OP_RECV) return 0; /* iovec is already imported */