From c6ce580716372d71cd119bacf73f14a62e9af2ea Mon Sep 17 00:00:00 2001 From: Doug Ledford Date: Fri, 21 Sep 2018 11:30:13 -0400 Subject: [PATCH] RDMA/umem: Fix potential addition overflow Given a large enough memory allocation, it is possible to wrap the pinned_vm counter. Check for addition overflow to prevent such eventualities. Fixes: 40ddacf2dda9 ("RDMA/umem: Don't hold mmap_sem for too long") Reported-by: Jason Gunthorpe Signed-off-by: Doug Ledford Reviewed-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/umem.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index 1886d77..8da1cf2 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -85,6 +85,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, struct page **page_list; struct vm_area_struct **vma_list; unsigned long lock_limit; + unsigned long new_pinned; unsigned long cur_base; struct mm_struct *mm; unsigned long npages; @@ -160,12 +161,13 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; down_write(&mm->mmap_sem); - mm->pinned_vm += npages; - if ((mm->pinned_vm > lock_limit) && !capable(CAP_IPC_LOCK)) { + if (check_add_overflow(mm->pinned_vm, npages, &new_pinned) || + (new_pinned > lock_limit && !capable(CAP_IPC_LOCK))) { up_write(&mm->mmap_sem); ret = -ENOMEM; - goto vma; + goto out; } + mm->pinned_vm = new_pinned; up_write(&mm->mmap_sem); cur_base = addr & PAGE_MASK; -- 2.7.4