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io_uring/net: save msghdr->msg_control for retries

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Commit cac9e4418f4cbd548ccb065b3adcafe073f7f7d2 upstream.

If the application sets ->msg_control and we have to later retry this
command, or if it got queued with IOSQE_ASYNC to begin with, then we
need to retain the original msg_control value. This is due to the net
stack overwriting this field with an in-kernel pointer, to copy it
in. Hitting that path for the second time will now fail the copy from
user, as it's attempting to copy from a non-user address.

Cc: stable@vger.kernel.org # 5.10+
Link: https://github.com/axboe/liburing/issues/880
Reported-and-tested-by: Marek Majkowski <marek@cloudflare.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jens Axboe 2023-06-23 07:38:14 -06:00 committed by Greg Kroah-Hartman
parent 5a7101d8fa
commit 5fdea4468f
1 changed files with 10 additions and 1 deletions
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11
io_uring/io_uring.c
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@ -581,6 +581,7 @@ struct io_sr_msg {
size_t len; size_t len;
size_t done_io; size_t done_io;
struct io_buffer *kbuf; struct io_buffer *kbuf;
void __user *msg_control;
}; };
struct io_open { struct io_open {
@ -4718,10 +4719,16 @@ static int io_setup_async_msg(struct io_kiocb *req,
static int io_sendmsg_copy_hdr(struct io_kiocb *req, static int io_sendmsg_copy_hdr(struct io_kiocb *req,
struct io_async_msghdr *iomsg) struct io_async_msghdr *iomsg)
{ {
struct io_sr_msg *sr = &req->sr_msg;
int ret;
iomsg->msg.msg_name = &iomsg->addr; iomsg->msg.msg_name = &iomsg->addr;
iomsg->free_iov = iomsg->fast_iov; iomsg->free_iov = iomsg->fast_iov;
return sendmsg_copy_msghdr(&iomsg->msg, req->sr_msg.umsg, ret = sendmsg_copy_msghdr(&iomsg->msg, req->sr_msg.umsg,
req->sr_msg.msg_flags, &iomsg->free_iov); req->sr_msg.msg_flags, &iomsg->free_iov);
/* save msg_control as sys_sendmsg() overwrites it */
sr->msg_control = iomsg->msg.msg_control;
return ret;
} }
static int io_sendmsg_prep_async(struct io_kiocb *req) static int io_sendmsg_prep_async(struct io_kiocb *req)
@ -4778,6 +4785,8 @@ static int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
if (ret) if (ret)
return ret; return ret;
kmsg = &iomsg; kmsg = &iomsg;
} else {
kmsg->msg.msg_control = sr->msg_control;
} }
flags = req->sr_msg.msg_flags; flags = req->sr_msg.msg_flags;