From: Pavel Begunkov asml.silence@gmail.com
mainline inclusion from mainline-5.9-rc1 commit 1bcb8c5d65a845e0ecb9e82237c399b29b8d15ea category: feature bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27 CVE: NA ---------------------------
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 asml.silence@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: yangerkun yangerkun@huawei.com Reviewed-by: zhangyi (F) yi.zhang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- fs/io_uring.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index e38a48c71a72..2535ac88d97a 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1874,7 +1874,7 @@ 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 @@ -1891,10 +1891,15 @@ 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; }
/*