Commit 69a62e03 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring/msg_ring: don't leave potentially dangling ->tctx pointer 



For remote posting of messages, req->tctx is assigned even though it
is never used. Rather than leave a dangling pointer, just clear it to
NULL and use the previous check for a valid submitter_task to gate on
whether or not the request should be terminated.

Reported-by: default avatarJann Horn <jannh@google.com>
Fixes: b6f58a3f ("io_uring: move struct io_kiocb from task_struct to io_uring_task")
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 2839ab71

io_uring/msg_ring.c

+2 −2
Original line number Diff line number Diff line
@@ -89,8 +89,7 @@ static void io_msg_tw_complete(struct io_kiocb *req, struct io_tw_state *ts) 
static int io_msg_remote_post(struct io_ring_ctx *ctx, struct io_kiocb *req,

			      int res, u32 cflags, u64 user_data)

{

	req->tctx = READ_ONCE(ctx->submitter_task->io_uring);

	if (!req->tctx) {

	if (!READ_ONCE(ctx->submitter_task)) {

		kmem_cache_free(req_cachep, req);

		return -EOWNERDEAD;

	}
@@ -98,6 +97,7 @@ static int io_msg_remote_post(struct io_ring_ctx *ctx, struct io_kiocb *req, 
	io_req_set_res(req, res, cflags);

	percpu_ref_get(&ctx->refs);

	req->ctx = ctx;

	req->tctx = NULL;

	req->io_task_work.func = io_msg_tw_complete;

	io_req_task_work_add_remote(req, ctx, IOU_F_TWQ_LAZY_WAKE);

	return 0;