From: Pavel Begunkov Date: Sat, 27 Jun 2020 11:04:56 +0000 (+0300) Subject: io_uring: fix feeding io-wq with uninit reqs X-Git-Tag: v5.10.7~2022^2~92 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1bcb8c5d65a845e0ecb9e82237c399b29b8d15ea;p=platform%2Fkernel%2Flinux-rpi.git io_uring: fix feeding io-wq with uninit reqs io_steal_work() can't be sure that @nxt has req->work properly set, so we can't pass it to io-wq as is. A dirty quick fix -- drag it through io_req_task_queue(), and always return NULL from io_steal_work(). e.g. [ 50.770161] BUG: kernel NULL pointer dereference, address: 00000000 [ 50.770164] #PF: supervisor write access in kernel mode [ 50.770164] #PF: error_code(0x0002) - not-present page [ 50.770168] CPU: 1 PID: 1448 Comm: io_wqe_worker-0 Tainted: G I 5.8.0-rc2-00035-g2237d76530eb-dirty #494 [ 50.770172] RIP: 0010:override_creds+0x19/0x30 ... [ 50.770183] io_worker_handle_work+0x25c/0x430 [ 50.770185] io_wqe_worker+0x2a0/0x350 [ 50.770190] kthread+0x136/0x180 [ 50.770194] ret_from_fork+0x22/0x30 Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe --- diff --git a/fs/io_uring.c b/fs/io_uring.c index 483457f..658949b 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1791,7 +1791,7 @@ static void io_put_req(struct io_kiocb *req) static struct io_wq_work *io_steal_work(struct io_kiocb *req) { - struct io_kiocb *link, *nxt = NULL; + struct io_kiocb *nxt = NULL; /* * A ref is owned by io-wq in which context we're. So, if that's the @@ -1808,10 +1808,15 @@ static struct io_wq_work *io_steal_work(struct io_kiocb *req) if ((nxt->flags & REQ_F_ISREG) && io_op_defs[nxt->opcode].hash_reg_file) io_wq_hash_work(&nxt->work, file_inode(nxt->file)); - link = io_prep_linked_timeout(nxt); - if (link) - nxt->flags |= REQ_F_QUEUE_TIMEOUT; - return &nxt->work; + io_req_task_queue(nxt); + /* + * If we're going to return actual work, here should be timeout prep: + * + * link = io_prep_linked_timeout(nxt); + * if (link) + * nxt->flags |= REQ_F_QUEUE_TIMEOUT; + */ + return NULL; } /*