io_uring/msg_ring: fix remote queue to disabled ring

IORING_SETUP_R_DISABLED rings don't have the submitter task set, so
it's not always safe to use ->submitter_task. Disallow posting msg_ring
messaged to disabled rings. Also add task NULL check for loosy sync
around testing for IORING_SETUP_R_DISABLED.

Cc: stable@vger.kernel.org
Fixes: 6d043ee1164ca ("io_uring: do msg_ring in target task via tw")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 2ac1cd8d23ea623cb371f7472a35a45cf9e358b6..0a4efada9b3c3dbc40677208174f9eb892470969 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3674,7 +3674,7 @@ static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
 
        if (ctx->flags & IORING_SETUP_SINGLE_ISSUER
            && !(ctx->flags & IORING_SETUP_R_DISABLED))
-               ctx->submitter_task = get_task_struct(current);
+               WRITE_ONCE(ctx->submitter_task, get_task_struct(current));
 
        file = io_uring_get_file(ctx);
        if (IS_ERR(file)) {
@@ -3868,7 +3868,7 @@ static int io_register_enable_rings(struct io_ring_ctx *ctx)
                return -EBADFD;
 
        if (ctx->flags & IORING_SETUP_SINGLE_ISSUER && !ctx->submitter_task)
-               ctx->submitter_task = get_task_struct(current);
+               WRITE_ONCE(ctx->submitter_task, get_task_struct(current));
 
        if (ctx->restrictions.registered)
                ctx->restricted = 1;

diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
index bb868447dcdfd632a93ec70b5b98c86987ff936d..15602a136821b510a8201f90daf541b0c9188e08 100644 (file)
--- a/io_uring/msg_ring.c
+++ b/io_uring/msg_ring.c
@@ -69,6 +69,10 @@ static int io_msg_exec_remote(struct io_kiocb *req, task_work_func_t func)
 {
        struct io_ring_ctx *ctx = req->file->private_data;
        struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
+       struct task_struct *task = READ_ONCE(ctx->submitter_task);
+
+       if (unlikely(!task))
+               return -EOWNERDEAD;
 
        init_task_work(&msg->tw, func);
        if (task_work_add(ctx->submitter_task, &msg->tw, TWA_SIGNAL))
@@ -114,6 +118,8 @@ static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags)
 
        if (msg->src_fd || msg->dst_fd || msg->flags)
                return -EINVAL;
+       if (target_ctx->flags & IORING_SETUP_R_DISABLED)
+               return -EBADFD;
 
        if (io_msg_need_remote(target_ctx))
                return io_msg_exec_remote(req, io_msg_tw_complete);
@@ -206,6 +212,8 @@ static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
 
        if (target_ctx == ctx)
                return -EINVAL;
+       if (target_ctx->flags & IORING_SETUP_R_DISABLED)
+               return -EBADFD;
        if (!src_file) {
                src_file = io_msg_grab_file(req, issue_flags);
                if (!src_file)