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 --- tools/testing/vma/shared.c | 131 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 131 insertions(+) create mode 100644 tools/testing/vma/shared.c (limited to 'tools/testing/vma/shared.c') diff --git a/tools/testing/vma/shared.c b/tools/testing/vma/shared.c new file mode 100644 index 000000000..2565a5aec --- /dev/null +++ b/tools/testing/vma/shared.c @@ -0,0 +1,131 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +#include "shared.h" + + +bool fail_prealloc; +unsigned long mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR; +unsigned long dac_mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR; +unsigned long stack_guard_gap = 256UL<vm_start = start; + vma->vm_end = end; + vma->vm_pgoff = pgoff; + vma->flags = vma_flags; + vma_assert_detached(vma); + + return vma; +} + +void detach_free_vma(struct vm_area_struct *vma) +{ + vma_mark_detached(vma); + vm_area_free(vma); +} + +struct vm_area_struct *alloc_and_link_vma(struct mm_struct *mm, + unsigned long start, unsigned long end, + pgoff_t pgoff, vma_flags_t vma_flags) +{ + struct vm_area_struct *vma = alloc_vma(mm, start, end, pgoff, vma_flags); + + if (vma == NULL) + return NULL; + + if (attach_vma(mm, vma)) { + detach_free_vma(vma); + return NULL; + } + + /* + * Reset this counter which we use to track whether writes have + * begun. Linking to the tree will have caused this to be incremented, + * which means we will get a false positive otherwise. + */ + vma->vm_lock_seq = UINT_MAX; + + return vma; +} + +void reset_dummy_anon_vma(void) +{ + dummy_anon_vma.was_cloned = false; + dummy_anon_vma.was_unlinked = false; +} + +int cleanup_mm(struct mm_struct *mm, struct vma_iterator *vmi) +{ + struct vm_area_struct *vma; + int count = 0; + + fail_prealloc = false; + reset_dummy_anon_vma(); + + vma_iter_set(vmi, 0); + for_each_vma(*vmi, vma) { + detach_free_vma(vma); + count++; + } + + mtree_destroy(&mm->mm_mt); + mm->map_count = 0; + return count; +} + +bool vma_write_started(struct vm_area_struct *vma) +{ + int seq = vma->vm_lock_seq; + + /* We reset after each check. */ + vma->vm_lock_seq = UINT_MAX; + + /* The vma_start_write() stub simply increments this value. */ + return seq > -1; +} + +void __vma_set_dummy_anon_vma(struct vm_area_struct *vma, + struct anon_vma_chain *avc, struct anon_vma *anon_vma) +{ + vma->anon_vma = anon_vma; + INIT_LIST_HEAD(&vma->anon_vma_chain); + list_add(&avc->same_vma, &vma->anon_vma_chain); + avc->anon_vma = vma->anon_vma; +} + +void vma_set_dummy_anon_vma(struct vm_area_struct *vma, + struct anon_vma_chain *avc) +{ + __vma_set_dummy_anon_vma(vma, avc, &dummy_anon_vma); +} + +struct task_struct *get_current(void) +{ + return &__current; +} + +unsigned long rlimit(unsigned int limit) +{ + return (unsigned long)-1; +} + +void vma_set_range(struct vm_area_struct *vma, + unsigned long start, unsigned long end, + pgoff_t pgoff) +{ + vma->vm_start = start; + vma->vm_end = end; + vma->vm_pgoff = pgoff; +} -- cgit v1.3.1