The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b4bd701ac469075d94ed9699a28755f2862252b9 Mon Sep 17 00:00:00 2001

From: Leon Romanovsky leonro@mellanox.com Date: Mon, 23 Apr 2018 17:01:52 +0300 Subject: [PATCH] RDMA/mlx5: Fix multiple NULL-ptr deref errors in rereg_mr flow

Failure in rereg MR releases UMEM but leaves the MR to be destroyed by the user. As a result the following scenario may happen: "create MR -> rereg MR with failure -> call to rereg MR again" and hit "NULL-ptr deref or user memory access" errors.

Ensure that rereg MR is only performed on a non-dead MR.

Cc: syzkaller syzkaller@googlegroups.com Cc: stable@vger.kernel.org # 4.5 Fixes: 395a8e4c32ea ("IB/mlx5: Refactoring register MR code") Reported-by: Noa Osherovich noaos@mellanox.com Signed-off-by: Leon Romanovsky leonro@mellanox.com Signed-off-by: Doug Ledford dledford@redhat.com

diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c index 1520a2f20f98..90a9c461cedc 100644 --- a/drivers/infiniband/hw/mlx5/mr.c +++ b/drivers/infiniband/hw/mlx5/mr.c @@ -866,25 +866,28 @@ static int mr_umem_get(struct ib_pd *pd, u64 start, u64 length, int *order) { struct mlx5_ib_dev *dev = to_mdev(pd->device); + struct ib_umem *u; int err;

- *umem = ib_umem_get(pd->uobject->context, start, length, - access_flags, 0); - err = PTR_ERR_OR_ZERO(*umem); + *umem = NULL; + + u = ib_umem_get(pd->uobject->context, start, length, access_flags, 0); + err = PTR_ERR_OR_ZERO(u); if (err) { - *umem = NULL; - mlx5_ib_err(dev, "umem get failed (%d)\n", err); + mlx5_ib_dbg(dev, "umem get failed (%d)\n", err); return err; }

- mlx5_ib_cont_pages(*umem, start, MLX5_MKEY_PAGE_SHIFT_MASK, npages, + mlx5_ib_cont_pages(u, start, MLX5_MKEY_PAGE_SHIFT_MASK, npages, page_shift, ncont, order); if (!*npages) { mlx5_ib_warn(dev, "avoid zero region\n"); - ib_umem_release(*umem); + ib_umem_release(u); return -EINVAL; }

+ *umem = u; + mlx5_ib_dbg(dev, "npages %d, ncont %d, order %d, page_shift %d\n", *npages, *ncont, *order, *page_shift);

@@ -1458,13 +1461,12 @@ int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start, int access_flags = flags & IB_MR_REREG_ACCESS ? new_access_flags : mr->access_flags; - u64 addr = (flags & IB_MR_REREG_TRANS) ? virt_addr : mr->umem->address; - u64 len = (flags & IB_MR_REREG_TRANS) ? length : mr->umem->length; int page_shift = 0; int upd_flags = 0; int npages = 0; int ncont = 0; int order = 0; + u64 addr, len; int err;

mlx5_ib_dbg(dev, "start 0x%llx, virt_addr 0x%llx, length 0x%llx, access_flags 0x%x\n", @@ -1472,6 +1474,17 @@ int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start,

atomic_sub(mr->npages, &dev->mdev->priv.reg_pages);

+ if (!mr->umem) + return -EINVAL; + + if (flags & IB_MR_REREG_TRANS) { + addr = virt_addr; + len = length; + } else { + addr = mr->umem->address; + len = mr->umem->length; + } + if (flags != IB_MR_REREG_PD) { /* * Replace umem. This needs to be done whether or not UMR is @@ -1479,6 +1492,7 @@ int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start, */ flags |= IB_MR_REREG_TRANS; ib_umem_release(mr->umem); + mr->umem = NULL; err = mr_umem_get(pd, addr, len, access_flags, &mr->umem, &npages, &page_shift, &ncont, &order); if (err)