diff options
| -rw-r--r-- | mm/vmalloc.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 78689cba178f..c5db9a7264d9 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -434,6 +434,27 @@ static void unmap_vmap_area(struct vmap_area *va) vunmap_page_range(va->va_start, va->va_end); } +static void vmap_debug_free_range(unsigned long start, unsigned long end) +{ + /* + * Unmap page tables and force a TLB flush immediately if + * CONFIG_DEBUG_PAGEALLOC is set. This catches use after free + * bugs similarly to those in linear kernel virtual address + * space after a page has been freed. + * + * All the lazy freeing logic is still retained, in order to + * minimise intrusiveness of this debugging feature. + * + * This is going to be *slow* (linear kernel virtual address + * debugging doesn't do a broadcast TLB flush so it is a lot + * faster). + */ +#ifdef CONFIG_DEBUG_PAGEALLOC + vunmap_page_range(start, end); + flush_tlb_kernel_range(start, end); +#endif +} + /* * lazy_max_pages is the maximum amount of virtual address space we gather up * before attempting to purge with a TLB flush. @@ -914,6 +935,7 @@ void vm_unmap_ram(const void *mem, unsigned int count) BUG_ON(addr & (PAGE_SIZE-1)); debug_check_no_locks_freed(mem, size); + vmap_debug_free_range(addr, addr+size); if (likely(count <= VMAP_MAX_ALLOC)) vb_free(mem, size); @@ -1130,6 +1152,8 @@ struct vm_struct *remove_vm_area(const void *addr) if (va && va->flags & VM_VM_AREA) { struct vm_struct *vm = va->private; struct vm_struct *tmp, **p; + + vmap_debug_free_range(va->va_start, va->va_end); free_unmap_vmap_area(va); vm->size -= PAGE_SIZE; |