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/statx.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 io_uring/statx.c (limited to 'io_uring/statx.c') diff --git a/io_uring/statx.c b/io_uring/statx.c new file mode 100644 index 000000000..7bcae4a6c --- /dev/null +++ b/io_uring/statx.c @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include + +#include + +#include "../fs/internal.h" + +#include "io_uring.h" +#include "statx.h" + +struct io_statx { + struct file *file; + int dfd; + unsigned int mask; + unsigned int flags; + struct delayed_filename filename; + struct statx __user *buffer; +}; + +int io_statx_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_statx *sx = io_kiocb_to_cmd(req, struct io_statx); + const char __user *path; + int ret; + + if (sqe->buf_index || sqe->splice_fd_in) + return -EINVAL; + if (req->flags & REQ_F_FIXED_FILE) + return -EBADF; + + sx->dfd = READ_ONCE(sqe->fd); + sx->mask = READ_ONCE(sqe->len); + path = u64_to_user_ptr(READ_ONCE(sqe->addr)); + sx->buffer = u64_to_user_ptr(READ_ONCE(sqe->addr2)); + sx->flags = READ_ONCE(sqe->statx_flags); + + ret = delayed_getname_uflags(&sx->filename, path, sx->flags); + + if (unlikely(ret)) + return ret; + + req->flags |= REQ_F_NEED_CLEANUP; + req->flags |= REQ_F_FORCE_ASYNC; + return 0; +} + +int io_statx(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_statx *sx = io_kiocb_to_cmd(req, struct io_statx); + CLASS(filename_complete_delayed, name)(&sx->filename); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = do_statx(sx->dfd, name, sx->flags, sx->mask, sx->buffer); + io_req_set_res(req, ret, 0); + return IOU_COMPLETE; +} + +void io_statx_cleanup(struct io_kiocb *req) +{ + struct io_statx *sx = io_kiocb_to_cmd(req, struct io_statx); + + dismiss_delayed_filename(&sx->filename); +} -- cgit v1.3.1