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: Jann Horn <jannh@xxxxxxxxxx>
Fixes: b6f58a3f4aa8 ("io_uring: move struct io_kiocb from task_struct to io_uring_task")
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
index bd3cd78d2dba..7e6f68e911f1 100644
--- a/io_uring/msg_ring.c
+++ b/io_uring/msg_ring.c
@@ -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;
--
Jens Axboe
