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/memmap.h | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 io_uring/memmap.h (limited to 'io_uring/memmap.h') diff --git a/io_uring/memmap.h b/io_uring/memmap.h new file mode 100644 index 000000000..f4cfbb6b9 --- /dev/null +++ b/io_uring/memmap.h @@ -0,0 +1,52 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef IO_URING_MEMMAP_H +#define IO_URING_MEMMAP_H + +#define IORING_MAP_OFF_PARAM_REGION 0x20000000ULL +#define IORING_MAP_OFF_ZCRX_REGION 0x30000000ULL + +#define IORING_OFF_ZCRX_SHIFT 16 + +struct page **io_pin_pages(unsigned long uaddr, unsigned long len, int *npages); + +#ifndef CONFIG_MMU +unsigned int io_uring_nommu_mmap_capabilities(struct file *file); +#endif +unsigned long io_uring_get_unmapped_area(struct file *file, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags); +int io_uring_mmap(struct file *file, struct vm_area_struct *vma); + +void io_free_region(struct user_struct *user, struct io_mapped_region *mr); +int io_create_region(struct io_ring_ctx *ctx, struct io_mapped_region *mr, + struct io_uring_region_desc *reg, + unsigned long mmap_offset); + +static inline void *io_region_get_ptr(struct io_mapped_region *mr) +{ + return mr->ptr; +} + +static inline bool io_region_is_set(struct io_mapped_region *mr) +{ + return !!mr->nr_pages; +} + +static inline void io_region_publish(struct io_ring_ctx *ctx, + struct io_mapped_region *src_region, + struct io_mapped_region *dst_region) +{ + /* + * Once published mmap can find it without holding only the ->mmap_lock + * and not ->uring_lock. + */ + guard(mutex)(&ctx->mmap_lock); + *dst_region = *src_region; +} + +static inline size_t io_region_size(struct io_mapped_region *mr) +{ + return (size_t) mr->nr_pages << PAGE_SHIFT; +} + +#endif -- cgit v1.3.1