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: [email protected] Fixes: 6d043ee ("io_uring: do msg_ring in target task via tw") Signed-off-by: Pavel Begunkov <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
sedwards · Jan 20, 2023 · 8579538 · 8579538
1 parent 56d8e31
commit 8579538
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Showing 2 changed files with 10 additions and 2 deletions.
diff --git 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
@@ -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)