From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- io_uring/rw.h | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 io_uring/rw.h (limited to 'io_uring/rw.h') diff --git a/io_uring/rw.h b/io_uring/rw.h new file mode 100644 index 000000000..9bd7fbf70 --- /dev/null +++ b/io_uring/rw.h @@ -0,0 +1,52 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include + +struct io_meta_state { + u32 seed; + struct iov_iter_state iter_meta; +}; + +struct io_async_rw { + struct iou_vec vec; + size_t bytes_done; + + struct_group(clear, + struct iov_iter iter; + struct iov_iter_state iter_state; + struct iovec fast_iov; + unsigned buf_group; + + /* + * wpq is for buffered io, while meta fields are used with + * direct io + */ + union { + struct wait_page_queue wpq; + struct { + struct uio_meta meta; + struct io_meta_state meta_state; + }; + }; + ); +}; + +int io_prep_read_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_prep_write_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_prep_readv_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_prep_writev_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_prep_readv(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_prep_writev(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_prep_read(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_prep_write(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_read(struct io_kiocb *req, unsigned int issue_flags); +int io_write(struct io_kiocb *req, unsigned int issue_flags); +int io_read_fixed(struct io_kiocb *req, unsigned int issue_flags); +int io_write_fixed(struct io_kiocb *req, unsigned int issue_flags); +void io_readv_writev_cleanup(struct io_kiocb *req); +void io_rw_fail(struct io_kiocb *req); +void io_req_rw_complete(struct io_tw_req tw_req, io_tw_token_t tw); +int io_read_mshot_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags); +void io_rw_cache_free(const void *entry); -- cgit v1.3.1