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: 40ddacf ("RDMA/umem: Don't hold mmap_sem for too long") Reported-by: Jason Gunthorpe <[email protected]> Signed-off-by: Doug Ledford <[email protected]> Reviewed-by: Leon Romanovsky <[email protected]> Signed-off-by: Jason Gunthorpe <[email protected]>
laijs · Sep 25, 2018 · c6ce580 · c6ce580
1 parent 3312d1c
commit c6ce580
Showing 1 changed file with 5 additions and 3 deletions.
diff --git 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;