On Sat, Feb 06, 2021 at 11:34:09AM +0600, Sabyrzhan Tasbolatov wrote: > syzbot found WARNING in qp_broker_alloc[1] in qp_host_alloc_queue() > when num_pages is 0x100001, giving queue_size + queue_page_size > bigger than KMALLOC_MAX_SIZE for kzalloc(), resulting order >= MAX_ORDER > condition. > > queue_size + queue_page_size=0x8000d8, where KMALLOC_MAX_SIZE=0x400000. > > > FYI, I've also noticed in vmci_queue_pair.c other SLAB allocations with no > length check that might exceed KMALLOC_MAX_SIZE as well, > but syzbot doesn't have reproduces for them. > > in qp_alloc_ppn_set(): > produce_ppns = > kmalloc_array(num_produce_pages, sizeof(*produce_ppns), > GFP_KERNEL); > [..] > consume_ppns = > kmalloc_array(num_consume_pages, sizeof(*consume_ppns), > GFP_KERNEL); > [..] > in qp_alloc_hypercall(): > msg_size = sizeof(*alloc_msg) + > (size_t) entry->num_ppns * ppn_size; > alloc_msg = kmalloc(msg_size, GFP_KERNEL); > [..] > in qp_broker_create(): > entry->local_mem = kcalloc(QPE_NUM_PAGES(entry->qp), > PAGE_SIZE, GFP_KERNEL); > > [1] > Call Trace: > alloc_pages include/linux/gfp.h:547 [inline] > kmalloc_order+0x40/0x130 mm/slab_common.c:837 > kmalloc_order_trace+0x15/0x70 mm/slab_common.c:853 > kmalloc_large include/linux/slab.h:481 [inline] > __kmalloc+0x257/0x330 mm/slub.c:3959 > kmalloc include/linux/slab.h:557 [inline] > kzalloc include/linux/slab.h:682 [inline] > qp_host_alloc_queue drivers/misc/vmw_vmci/vmci_queue_pair.c:540 [inline] > qp_broker_create drivers/misc/vmw_vmci/vmci_queue_pair.c:1351 [inline] > qp_broker_alloc+0x936/0x2740 drivers/misc/vmw_vmci/vmci_queue_pair.c:1739 > > Reported-by: syzbot+15ec7391f3d6a1a7c...@syzkaller.appspotmail.com > Signed-off-by: Sabyrzhan Tasbolatov <snovit...@gmail.com> > --- > drivers/misc/vmw_vmci/vmci_queue_pair.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c > b/drivers/misc/vmw_vmci/vmci_queue_pair.c > index c49065887e8f..f6af406fda80 100644 > --- a/drivers/misc/vmw_vmci/vmci_queue_pair.c > +++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c > @@ -537,6 +537,11 @@ static struct vmci_queue *qp_host_alloc_queue(u64 size) > > queue_page_size = num_pages * sizeof(*queue->kernel_if->u.h.page); > > + if (queue_size + queue_page_size > KMALLOC_MAX_SIZE) { > + pr_warn("too big queue to allocate\n");
As this is controllable by userspace, you just provided a way to flood the kernel logs. Please make this a dev_dbg() call instead, if you really want to see it. Otherwise just return NULL, no need to report anything, right? thanks, greg k-h