RDMA/mlx5: Fix releasing unallocated memory in dereg MR flow

[ Upstream commit f0ae4afe3d35e67db042c58a52909e06262b740f ]

For the case of IB_MR_TYPE_DM the mr does doesn't have a umem, even though
it is a user MR. This causes function mlx5_free_priv_descs() to think that
it is a kernel MR, leading to wrongly accessing mr->descs that will get
wrong values in the union which leads to attempt to release resources that
were not allocated in the first place.

For example:
 DMA-API: mlx5_core 0000:08:00.1: device driver tries to free DMA memory it has not allocated [device address=0x0000000000000000] [size=0 bytes]
 WARNING: CPU: 8 PID: 1021 at kernel/dma/debug.c:961 check_unmap+0x54f/0x8b0
 RIP: 0010:check_unmap+0x54f/0x8b0
 Call Trace:
  debug_dma_unmap_page+0x57/0x60
  mlx5_free_priv_descs+0x57/0x70 [mlx5_ib]
  mlx5_ib_dereg_mr+0x1fb/0x3d0 [mlx5_ib]
  ib_dereg_mr_user+0x60/0x140 [ib_core]
  uverbs_destroy_uobject+0x59/0x210 [ib_uverbs]
  uobj_destroy+0x3f/0x80 [ib_uverbs]
  ib_uverbs_cmd_verbs+0x435/0xd10 [ib_uverbs]
  ? uverbs_finalize_object+0x50/0x50 [ib_uverbs]
  ? lock_acquire+0xc4/0x2e0
  ? lock_acquired+0x12/0x380
  ? lock_acquire+0xc4/0x2e0
  ? lock_acquire+0xc4/0x2e0
  ? ib_uverbs_ioctl+0x7c/0x140 [ib_uverbs]
  ? lock_release+0x28a/0x400
  ib_uverbs_ioctl+0xc0/0x140 [ib_uverbs]
  ? ib_uverbs_ioctl+0x7c/0x140 [ib_uverbs]
  __x64_sys_ioctl+0x7f/0xb0
  do_syscall_64+0x38/0x90

Fix it by reorganizing the dereg flow and mlx5_ib_mr structure:
 - Move the ib_umem field into the user MRs structure in the union as it's
   applicable only there.
 - Function mlx5_ib_dereg_mr() will now call mlx5_free_priv_descs() only
   in case there isn't udata, which indicates that this isn't a user MR.

Fixes: f18ec4223117 ("RDMA/mlx5: Use a union inside mlx5_ib_mr")
Link: https://lore.kernel.org/r/66bb1dd253c1fd7ceaa9fc411061eefa457b86fb.1637581144.git.leonro@nvidia.com
Signed-off-by: Alaa Hleihel <alaa@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index bf20a38..6204ae2 100644 (file)
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -641,7 +641,6 @@ struct mlx5_ib_mr {
 
        /* User MR data */
        struct mlx5_cache_ent *cache_ent;
-       struct ib_umem *umem;
 
        /* This is zero'd when the MR is allocated */
        union {
@@ -653,7 +652,7 @@ struct mlx5_ib_mr {
                        struct list_head list;
                };
 
-               /* Used only by kernel MRs (umem == NULL) */
+               /* Used only by kernel MRs */
                struct {
                        void *descs;
                        void *descs_alloc;
@@ -675,8 +674,9 @@ struct mlx5_ib_mr {
                        int data_length;
                };
 
-               /* Used only by User MRs (umem != NULL) */
+               /* Used only by User MRs */
                struct {
+                       struct ib_umem *umem;
                        unsigned int page_shift;
                        /* Current access_flags */
                        int access_flags;

diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 22e2f4d..69b2ce4 100644 (file)
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1911,19 +1911,18 @@ err:
        return ret;
 }
 
-static void
-mlx5_free_priv_descs(struct mlx5_ib_mr *mr)
+static void mlx5_free_priv_descs(struct mlx5_ib_mr *mr)
 {
-       if (!mr->umem && mr->descs) {
-               struct ib_device *device = mr->ibmr.device;
-               int size = mr->max_descs * mr->desc_size;
-               struct mlx5_ib_dev *dev = to_mdev(device);
+       struct mlx5_ib_dev *dev = to_mdev(mr->ibmr.device);
+       int size = mr->max_descs * mr->desc_size;
 
-               dma_unmap_single(&dev->mdev->pdev->dev, mr->desc_map, size,
-                                DMA_TO_DEVICE);
-               kfree(mr->descs_alloc);
-               mr->descs = NULL;
-       }
+       if (!mr->descs)
+               return;
+
+       dma_unmap_single(&dev->mdev->pdev->dev, mr->desc_map, size,
+                        DMA_TO_DEVICE);
+       kfree(mr->descs_alloc);
+       mr->descs = NULL;
 }
 
 int mlx5_ib_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
@@ -1999,7 +1998,8 @@ int mlx5_ib_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
        if (mr->cache_ent) {
                mlx5_mr_cache_free(dev, mr);
        } else {
-               mlx5_free_priv_descs(mr);
+               if (!udata)
+                       mlx5_free_priv_descs(mr);
                kfree(mr);
        }
        return 0;
@@ -2086,7 +2086,6 @@ static struct mlx5_ib_mr *mlx5_ib_alloc_pi_mr(struct ib_pd *pd,
        if (err)
                goto err_free_in;
 
-       mr->umem = NULL;
        kfree(in);
 
        return mr;
@@ -2213,7 +2212,6 @@ static struct ib_mr *__mlx5_ib_alloc_mr(struct ib_pd *pd,
        }
 
        mr->ibmr.device = pd->device;
-       mr->umem = NULL;
 
        switch (mr_type) {
        case IB_MR_TYPE_MEM_REG: