drm/amdgpu: unwind properly in amdgpu_cs_parser_init()

The amdgpu_cs_parser_init() function doesn't clean up after itself but
instead the caller uses a free everything function amdgpu_cs_parser_fini()
on failure.  This style of error handling is often buggy.  In this
example, we call "drm_free_large(parser->chunks[i].kdata);" when it is
an unintialized pointer or when "parser->chunks" is NULL.

I fixed this bug by adding unwind code so that it frees everything that
it allocates.

I also mode some other very minor changes:
1) Renamed "r" to "ret".
2) Moved the chunk_array allocation to the start of the function.
3) Removed some initializers which are no longer needed.

Reviewed-by: Christian König <christian.koenig@amd.com>
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index b74b6a8..749420f 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -154,42 +154,41 @@ int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p, void *data)
 {
        union drm_amdgpu_cs *cs = data;
        uint64_t *chunk_array_user;
-       uint64_t *chunk_array = NULL;
+       uint64_t *chunk_array;
        struct amdgpu_fpriv *fpriv = p->filp->driver_priv;
        unsigned size, i;
-       int r = 0;
+       int ret;
 
-       if (!cs->in.num_chunks)
-               goto out;
+       if (cs->in.num_chunks == 0)
+               return 0;
+
+       chunk_array = kmalloc_array(cs->in.num_chunks, sizeof(uint64_t), GFP_KERNEL);
+       if (!chunk_array)
+               return -ENOMEM;
 
        p->ctx = amdgpu_ctx_get(fpriv, cs->in.ctx_id);
        if (!p->ctx) {
-               r = -EINVAL;
-               goto out;
+               ret = -EINVAL;
+               goto free_chunk;
        }
+
        p->bo_list = amdgpu_bo_list_get(fpriv, cs->in.bo_list_handle);
 
        /* get chunks */
        INIT_LIST_HEAD(&p->validated);
-       chunk_array = kmalloc_array(cs->in.num_chunks, sizeof(uint64_t), GFP_KERNEL);
-       if (chunk_array == NULL) {
-               r = -ENOMEM;
-               goto out;
-       }
-
        chunk_array_user = (uint64_t __user *)(cs->in.chunks);
        if (copy_from_user(chunk_array, chunk_array_user,
                           sizeof(uint64_t)*cs->in.num_chunks)) {
-               r = -EFAULT;
-               goto out;
+               ret = -EFAULT;
+               goto put_bo_list;
        }
 
        p->nchunks = cs->in.num_chunks;
        p->chunks = kmalloc_array(p->nchunks, sizeof(struct amdgpu_cs_chunk),
                            GFP_KERNEL);
-       if (p->chunks == NULL) {
-               r = -ENOMEM;
-               goto out;
+       if (!p->chunks) {
+               ret = -ENOMEM;
+               goto put_bo_list;
        }
 
        for (i = 0; i < p->nchunks; i++) {
@@ -200,8 +199,9 @@ int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p, void *data)
                chunk_ptr = (void __user *)chunk_array[i];
                if (copy_from_user(&user_chunk, chunk_ptr,
                                       sizeof(struct drm_amdgpu_cs_chunk))) {
-                       r = -EFAULT;
-                       goto out;
+                       ret = -EFAULT;
+                       i--;
+                       goto free_partial_kdata;
                }
                p->chunks[i].chunk_id = user_chunk.chunk_id;
                p->chunks[i].length_dw = user_chunk.length_dw;
@@ -212,13 +212,14 @@ int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p, void *data)
 
                p->chunks[i].kdata = drm_malloc_ab(size, sizeof(uint32_t));
                if (p->chunks[i].kdata == NULL) {
-                       r = -ENOMEM;
-                       goto out;
+                       ret = -ENOMEM;
+                       i--;
+                       goto free_partial_kdata;
                }
                size *= sizeof(uint32_t);
                if (copy_from_user(p->chunks[i].kdata, cdata, size)) {
-                       r = -EFAULT;
-                       goto out;
+                       ret = -EFAULT;
+                       goto free_partial_kdata;
                }
 
                switch (p->chunks[i].chunk_id) {
@@ -238,15 +239,15 @@ int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p, void *data)
                                gobj = drm_gem_object_lookup(p->adev->ddev,
                                                             p->filp, handle);
                                if (gobj == NULL) {
-                                       r = -EINVAL;
-                                       goto out;
+                                       ret = -EINVAL;
+                                       goto free_partial_kdata;
                                }
 
                                p->uf.bo = gem_to_amdgpu_bo(gobj);
                                p->uf.offset = fence_data->offset;
                        } else {
-                               r = -EINVAL;
-                               goto out;
+                               ret = -EINVAL;
+                               goto free_partial_kdata;
                        }
                        break;
 
@@ -254,19 +255,35 @@ int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p, void *data)
                        break;
 
                default:
-                       r = -EINVAL;
-                       goto out;
+                       ret = -EINVAL;
+                       goto free_partial_kdata;
                }
        }
 
 
        p->ibs = kcalloc(p->num_ibs, sizeof(struct amdgpu_ib), GFP_KERNEL);
-       if (!p->ibs)
-               r = -ENOMEM;
+       if (!p->ibs) {
+               ret = -ENOMEM;
+               goto free_all_kdata;
+       }
 
-out:
        kfree(chunk_array);
-       return r;
+       return 0;
+
+free_all_kdata:
+       i = p->nchunks - 1;
+free_partial_kdata:
+       for (; i >= 0; i--)
+               drm_free_large(p->chunks[i].kdata);
+       kfree(p->chunks);
+put_bo_list:
+       if (p->bo_list)
+               amdgpu_bo_list_put(p->bo_list);
+       amdgpu_ctx_put(p->ctx);
+free_chunk:
+       kfree(chunk_array);
+
+       return ret;
 }
 
 /* Returns how many bytes TTM can move per IB.
@@ -810,7 +827,7 @@ int amdgpu_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
        r = amdgpu_cs_parser_init(parser, data);
        if (r) {
                DRM_ERROR("Failed to initialize parser !\n");
-               amdgpu_cs_parser_fini(parser, r, false);
+               kfree(parser);
                up_read(&adev->exclusive_lock);
                r = amdgpu_cs_handle_lockup(adev, r);
                return r;