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authorPavel Begunkov <asml.silence@gmail.com>2020-03-13 22:29:14 +0300
committerJens Axboe <axboe@kernel.dk>2020-03-14 16:57:41 -0600
commitf1d96a8fcbbbb22d4fbc1d69eaaa678bbb0ff6e2 (patch)
tree8a3a3856eec59a94b9a2f7bba37127b982cf7d48
parent805b13adde3964c78cba125a15527e88c19f87b3 (diff)
io_uring: NULL-deref for IOSQE_{ASYNC,DRAIN}
Processing links, io_submit_sqe() prepares requests, drops sqes, and passes them with sqe=NULL to io_queue_sqe(). There IOSQE_DRAIN and/or IOSQE_ASYNC requests will go through the same prep, which doesn't expect sqe=NULL and fail with NULL pointer deference. Always do full prepare including io_alloc_async_ctx() for linked requests, and then it can skip the second preparation. Cc: stable@vger.kernel.org # 5.5 Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io_uring.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1b2517291b78..b1fbc4424aa6 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4131,6 +4131,9 @@ static int io_req_defer_prep(struct io_kiocb *req,
{
ssize_t ret = 0;
+ if (!sqe)
+ return 0;
+
if (io_op_defs[req->opcode].file_table) {
ret = io_grab_files(req);
if (unlikely(ret))
@@ -4907,6 +4910,11 @@ err_req:
if (sqe_flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK)) {
req->flags |= REQ_F_LINK;
INIT_LIST_HEAD(&req->link_list);
+
+ if (io_alloc_async_ctx(req)) {
+ ret = -EAGAIN;
+ goto err_req;
+ }
ret = io_req_defer_prep(req, sqe);
if (ret)
req->flags |= REQ_F_FAIL_LINK;