From f1d96a8fcbbbb22d4fbc1d69eaaa678bbb0ff6e2 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Fri, 13 Mar 2020 22:29:14 +0300 Subject: 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 Signed-off-by: Jens Axboe --- fs/io_uring.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'fs/io_uring.c') 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; -- cgit From 4022e7af86be2dd62975dedb6b7ea551d108695e Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 19 Mar 2020 19:23:18 -0600 Subject: io_uring: make sure openat/openat2 honor rlimit nofile Dmitry reports that a test case shows that io_uring isn't honoring a modified rlimit nofile setting. get_unused_fd_flags() checks the task signal->rlimi[] for the limits. As this isn't easily inheritable, provide a __get_unused_fd_flags() that takes the value instead. Then we can grab it when the request is prepared (from the original task), and pass that in when we do the async part part of the open. Reported-by: Dmitry Kadashev Tested-by: Dmitry Kadashev Acked-by: David S. Miller Signed-off-by: Jens Axboe --- fs/io_uring.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'fs/io_uring.c') diff --git a/fs/io_uring.c b/fs/io_uring.c index b1fbc4424aa6..fe5ded7c74ef 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -397,6 +397,7 @@ struct io_open { struct filename *filename; struct statx __user *buffer; struct open_how how; + unsigned long nofile; }; struct io_files_update { @@ -2577,6 +2578,7 @@ static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) return ret; } + req->open.nofile = rlimit(RLIMIT_NOFILE); req->flags |= REQ_F_NEED_CLEANUP; return 0; } @@ -2618,6 +2620,7 @@ static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) return ret; } + req->open.nofile = rlimit(RLIMIT_NOFILE); req->flags |= REQ_F_NEED_CLEANUP; return 0; } @@ -2636,7 +2639,7 @@ static int io_openat2(struct io_kiocb *req, struct io_kiocb **nxt, if (ret) goto err; - ret = get_unused_fd_flags(req->open.how.flags); + ret = __get_unused_fd_flags(req->open.how.flags, req->open.nofile); if (ret < 0) goto err; -- cgit From 09952e3e7826119ddd4357c453d54bcc7ef25156 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 19 Mar 2020 20:16:56 -0600 Subject: io_uring: make sure accept honor rlimit nofile Just like commit 4022e7af86be, this fixes the fact that IORING_OP_ACCEPT ends up using get_unused_fd_flags(), which checks current->signal->rlim[] for limits. Add an extra argument to __sys_accept4_file() that allows us to pass in the proper nofile limit, and grab it at request prep time. Acked-by: David S. Miller Signed-off-by: Jens Axboe --- fs/io_uring.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'fs/io_uring.c') diff --git a/fs/io_uring.c b/fs/io_uring.c index fe5ded7c74ef..3affd96a98ba 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -343,6 +343,7 @@ struct io_accept { struct sockaddr __user *addr; int __user *addr_len; int flags; + unsigned long nofile; }; struct io_sync { @@ -3324,6 +3325,7 @@ static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) accept->addr = u64_to_user_ptr(READ_ONCE(sqe->addr)); accept->addr_len = u64_to_user_ptr(READ_ONCE(sqe->addr2)); accept->flags = READ_ONCE(sqe->accept_flags); + accept->nofile = rlimit(RLIMIT_NOFILE); return 0; #else return -EOPNOTSUPP; @@ -3340,7 +3342,8 @@ static int __io_accept(struct io_kiocb *req, struct io_kiocb **nxt, file_flags = force_nonblock ? O_NONBLOCK : 0; ret = __sys_accept4_file(req->file, file_flags, accept->addr, - accept->addr_len, accept->flags); + accept->addr_len, accept->flags, + accept->nofile); if (ret == -EAGAIN && force_nonblock) return -EAGAIN; if (ret == -ERESTARTSYS) -- cgit