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/tctx.h | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 io_uring/tctx.h (limited to 'io_uring/tctx.h') diff --git a/io_uring/tctx.h b/io_uring/tctx.h new file mode 100644 index 000000000..76ad1ad45 --- /dev/null +++ b/io_uring/tctx.h @@ -0,0 +1,34 @@ +// SPDX-License-Identifier: GPL-2.0 + +struct io_tctx_node { + struct list_head ctx_node; + struct task_struct *task; + struct io_ring_ctx *ctx; +}; + +struct io_uring_task *io_uring_alloc_task_context(struct task_struct *task, + struct io_ring_ctx *ctx); +void io_uring_del_tctx_node(unsigned long index); +int __io_uring_add_tctx_node(struct io_ring_ctx *ctx); +int __io_uring_add_tctx_node_from_submit(struct io_ring_ctx *ctx); +void io_uring_clean_tctx(struct io_uring_task *tctx); +void io_uring_free_tctx(struct task_struct *tsk); + +void io_uring_unreg_ringfd(void); +int io_ringfd_register(struct io_ring_ctx *ctx, void __user *__arg, + unsigned nr_args); +int io_ringfd_unregister(struct io_ring_ctx *ctx, void __user *__arg, + unsigned nr_args); + +/* + * Note that this task has used io_uring. We use it for cancelation purposes. + */ +static inline int io_uring_add_tctx_node(struct io_ring_ctx *ctx) +{ + struct io_uring_task *tctx = current->io_uring; + + if (likely(tctx && tctx->last == ctx)) + return 0; + + return __io_uring_add_tctx_node_from_submit(ctx); +} -- cgit v1.3.1