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io_uring: don't read user-shared sqe flags twice 

Don't re-read userspace-shared sqe->flags, it can be exploited.
sqe->flags are copied into req->flags in io_submit_sqe(), check them
there instead.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
alistair/sensors
Pavel Begunkov 2020-04-08 08:58:46 +03:00 committed by Jens Axboe
parent 0553b8bda8
commit 9c280f9087
1 changed files with 8 additions and 12 deletions
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20
fs/io_uring.c
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@ -2931,7 +2931,7 @@ static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (sqe->ioprio || sqe->buf_index)
return -EINVAL;
if (sqe->flags & IOSQE_FIXED_FILE)
if (req->flags & REQ_F_FIXED_FILE)
return -EBADF;
if (req->flags & REQ_F_NEED_CLEANUP)
return 0;
@ -2964,7 +2964,7 @@ static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (sqe->ioprio || sqe->buf_index)
return -EINVAL;
if (sqe->flags & IOSQE_FIXED_FILE)
if (req->flags & REQ_F_FIXED_FILE)
return -EBADF;
if (req->flags & REQ_F_NEED_CLEANUP)
return 0;
@ -3318,7 +3318,7 @@ static int io_statx_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (sqe->ioprio || sqe->buf_index)
return -EINVAL;
if (sqe->flags & IOSQE_FIXED_FILE)
if (req->flags & REQ_F_FIXED_FILE)
return -EBADF;
if (req->flags & REQ_F_NEED_CLEANUP)
return 0;
@ -3395,7 +3395,7 @@ static int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (sqe->ioprio || sqe->off || sqe->addr || sqe->len ||
sqe->rw_flags || sqe->buf_index)
return -EINVAL;
if (sqe->flags & IOSQE_FIXED_FILE)
if (req->flags & REQ_F_FIXED_FILE)
return -EBADF;
req->close.fd = READ_ONCE(sqe->fd);
@ -5366,15 +5366,10 @@ static int io_file_get(struct io_submit_state *state, struct io_kiocb *req,
}
static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,
const struct io_uring_sqe *sqe)
int fd, unsigned int flags)
{
unsigned flags;
int fd;
bool fixed;
flags = READ_ONCE(sqe->flags);
fd = READ_ONCE(sqe->fd);
if (!io_req_needs_file(req, fd))
return 0;
@ -5616,7 +5611,7 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
{
struct io_ring_ctx *ctx = req->ctx;
unsigned int sqe_flags;
int ret, id;
int ret, id, fd;
sqe_flags = READ_ONCE(sqe->flags);
@ -5647,7 +5642,8 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
IOSQE_ASYNC | IOSQE_FIXED_FILE |
IOSQE_BUFFER_SELECT);
ret = io_req_set_file(state, req, sqe);
fd = READ_ONCE(sqe->fd);
ret = io_req_set_file(state, req, fd, sqe_flags);
if (unlikely(ret)) {
err_req:
io_cqring_add_event(req, ret);