diff options
Diffstat (limited to 'kernel/events/core.c')
| -rw-r--r-- | kernel/events/core.c | 36 |
1 files changed, 28 insertions, 8 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 22fdf0c187cd..8060c2857bb2 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6842,10 +6842,20 @@ static vm_fault_t perf_mmap_pfn_mkwrite(struct vm_fault *vmf) return vmf->pgoff == 0 ? 0 : VM_FAULT_SIGBUS; } +static int perf_mmap_may_split(struct vm_area_struct *vma, unsigned long addr) +{ + /* + * Forbid splitting perf mappings to prevent refcount leaks due to + * the resulting non-matching offsets and sizes. See open()/close(). + */ + return -EINVAL; +} + static const struct vm_operations_struct perf_mmap_vmops = { .open = perf_mmap_open, .close = perf_mmap_close, /* non mergeable */ .pfn_mkwrite = perf_mmap_pfn_mkwrite, + .may_split = perf_mmap_may_split, }; static int map_range(struct perf_buffer *rb, struct vm_area_struct *vma) @@ -7051,8 +7061,6 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) ret = 0; goto unlock; } - - atomic_set(&rb->aux_mmap_count, 1); } user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10); @@ -7115,15 +7123,16 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) perf_event_update_time(event); perf_event_init_userpage(event); perf_event_update_userpage(event); + ret = 0; } else { ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages, event->attr.aux_watermark, flags); - if (!ret) + if (!ret) { + atomic_set(&rb->aux_mmap_count, 1); rb->aux_mmap_locked = extra; + } } - ret = 0; - unlock: if (!ret) { atomic_long_add(user_extra, &user->locked_vm); @@ -7131,6 +7140,7 @@ unlock: atomic_inc(&event->mmap_count); } else if (rb) { + /* AUX allocation failed */ atomic_dec(&rb->mmap_count); } aux_unlock: @@ -7138,6 +7148,9 @@ aux_unlock: mutex_unlock(aux_mutex); mutex_unlock(&event->mmap_mutex); + if (ret) + return ret; + /* * Since pinned accounting is per vm we cannot allow fork() to copy our * vma. @@ -7145,13 +7158,20 @@ aux_unlock: vm_flags_set(vma, VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP); vma->vm_ops = &perf_mmap_vmops; - if (!ret) - ret = map_range(rb, vma); - mapped = get_mapped(event, event_mapped); if (mapped) mapped(event, vma->vm_mm); + /* + * Try to map it into the page table. On fail, invoke + * perf_mmap_close() to undo the above, as the callsite expects + * full cleanup in this case and therefore does not invoke + * vmops::close(). + */ + ret = map_range(rb, vma); + if (ret) + perf_mmap_close(vma); + return ret; } |