On Tue, Jun 13, 2023 at 08:32:11PM +0800, Shuai Xue wrote: > kernel/events/ring_buffer.c | 13 +++++++++++++ > tools/perf/Documentation/perf-record.txt | 3 ++- > 2 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c > index a0433f37b024..e514aaba9d42 100644 > --- a/kernel/events/ring_buffer.c > +++ b/kernel/events/ring_buffer.c > @@ -673,6 +673,7 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event, > bool overwrite = !(flags & RING_BUFFER_WRITABLE); > int node = (event->cpu == -1) ? -1 : cpu_to_node(event->cpu); > int ret = -ENOMEM, max_order; > + size_t bytes; > > if (!has_aux(event)) > return -EOPNOTSUPP; > @@ -699,6 +700,18 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event, > watermark = 0; > } > > + /* > + * 'rb->aux_pages' allocated by kcalloc() is a pointer array which is > + * used to maintains AUX trace pages. The allocated page for this array > + * is physically contiguous (and virtually contiguous) with an order of > + * 0..MAX_ORDER. If the size of pointer array crosses the limitation set > + * by MAX_ORDER, it reveals a WARNING. > + * > + * So bail out early if the request AUX area is out of bound. > + */ > + if (check_mul_overflow(nr_pages, sizeof(void *), &bytes) || > + get_order(bytes) > MAX_ORDER) > + return -EINVAL; This is all quite horrific :/ What's wrong with something simple: /* Can't allocate more than MAX_ORDER */ if (get_order((unsigned long)nr_pages * sizeof(void*)) > MAX_ORDER) return -EINVAL; If you're on 32bit then nr_pages should never be big enough to overflow, fundamentally you'll only have 32-PAGE_SHIFT bits in nr_pages. > rb->aux_pages = kcalloc_node(nr_pages, sizeof(void *), GFP_KERNEL, > node);
