If user space calls unreference on a user_dmabuf it will typically kill the struct ttm_base_object member which is responsible for the user-space visibility. However the dmabuf part may still be alive and refcounted. In some situations, like for shared guest-backed surface referencing/opening, the driver may try to reference the struct ttm_base_object member again, causing an immediate kernel warning and a later kernel NULL pointer dereference.
Fix this by always maintaining a reference on the struct ttm_base_object member, in situations where it might subsequently be referenced.
Cc: stable@vger.kernel.org Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Reviewed-by: Brian Paul brianp@vmware.com Reviewed-by: Sinclair Yeh syeh@vmware.com --- drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 6 ++++-- drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 6 ++++-- drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c | 2 +- drivers/gpu/drm/vmwgfx/vmwgfx_resource.c | 29 +++++++++++++++++++++-------- drivers/gpu/drm/vmwgfx/vmwgfx_shader.c | 2 +- drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 11 ++++++++--- 6 files changed, 39 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h index 8f40692..b60b41f 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h @@ -631,7 +631,8 @@ extern int vmw_user_dmabuf_alloc(struct vmw_private *dev_priv, uint32_t size, bool shareable, uint32_t *handle, - struct vmw_dma_buffer **p_dma_buf); + struct vmw_dma_buffer **p_dma_buf, + struct ttm_base_object **p_base); extern int vmw_user_dmabuf_reference(struct ttm_object_file *tfile, struct vmw_dma_buffer *dma_buf, uint32_t *handle); @@ -645,7 +646,8 @@ extern uint32_t vmw_dmabuf_validate_node(struct ttm_buffer_object *bo, uint32_t cur_validate_node); extern void vmw_dmabuf_validate_clear(struct ttm_buffer_object *bo); extern int vmw_user_dmabuf_lookup(struct ttm_object_file *tfile, - uint32_t id, struct vmw_dma_buffer **out); + uint32_t id, struct vmw_dma_buffer **out, + struct ttm_base_object **base); extern int vmw_stream_claim_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv); extern int vmw_stream_unref_ioctl(struct drm_device *dev, void *data, diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c index b565654..5da5de0 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c @@ -1236,7 +1236,8 @@ static int vmw_translate_mob_ptr(struct vmw_private *dev_priv, struct vmw_relocation *reloc; int ret;
- ret = vmw_user_dmabuf_lookup(sw_context->fp->tfile, handle, &vmw_bo); + ret = vmw_user_dmabuf_lookup(sw_context->fp->tfile, handle, &vmw_bo, + NULL); if (unlikely(ret != 0)) { DRM_ERROR("Could not find or use MOB buffer.\n"); ret = -EINVAL; @@ -1296,7 +1297,8 @@ static int vmw_translate_guest_ptr(struct vmw_private *dev_priv, struct vmw_relocation *reloc; int ret;
- ret = vmw_user_dmabuf_lookup(sw_context->fp->tfile, handle, &vmw_bo); + ret = vmw_user_dmabuf_lookup(sw_context->fp->tfile, handle, &vmw_bo, + NULL); if (unlikely(ret != 0)) { DRM_ERROR("Could not find or use GMR region.\n"); ret = -EINVAL; diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c b/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c index 76069f0..222c9c2 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_overlay.c @@ -484,7 +484,7 @@ int vmw_overlay_ioctl(struct drm_device *dev, void *data, goto out_unlock; }
- ret = vmw_user_dmabuf_lookup(tfile, arg->handle, &buf); + ret = vmw_user_dmabuf_lookup(tfile, arg->handle, &buf, NULL); if (ret) goto out_unlock;
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c index c1912f8..e57667c 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c @@ -354,7 +354,7 @@ int vmw_user_lookup_handle(struct vmw_private *dev_priv, }
*out_surf = NULL; - ret = vmw_user_dmabuf_lookup(tfile, handle, out_buf); + ret = vmw_user_dmabuf_lookup(tfile, handle, out_buf, NULL); return ret; }
@@ -481,7 +481,8 @@ int vmw_user_dmabuf_alloc(struct vmw_private *dev_priv, uint32_t size, bool shareable, uint32_t *handle, - struct vmw_dma_buffer **p_dma_buf) + struct vmw_dma_buffer **p_dma_buf, + struct ttm_base_object **p_base) { struct vmw_user_dma_buffer *user_bo; struct ttm_buffer_object *tmp; @@ -515,6 +516,10 @@ int vmw_user_dmabuf_alloc(struct vmw_private *dev_priv, }
*p_dma_buf = &user_bo->dma; + if (p_base) { + *p_base = &user_bo->prime.base; + kref_get(&(*p_base)->refcount); + } *handle = user_bo->prime.base.hash.key;
out_no_base_object: @@ -631,6 +636,7 @@ int vmw_user_dmabuf_synccpu_ioctl(struct drm_device *dev, void *data, struct vmw_dma_buffer *dma_buf; struct vmw_user_dma_buffer *user_bo; struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile; + struct ttm_base_object *buffer_base; int ret;
if ((arg->flags & (drm_vmw_synccpu_read | drm_vmw_synccpu_write)) == 0 @@ -643,7 +649,8 @@ int vmw_user_dmabuf_synccpu_ioctl(struct drm_device *dev, void *data,
switch (arg->op) { case drm_vmw_synccpu_grab: - ret = vmw_user_dmabuf_lookup(tfile, arg->handle, &dma_buf); + ret = vmw_user_dmabuf_lookup(tfile, arg->handle, &dma_buf, + &buffer_base); if (unlikely(ret != 0)) return ret;
@@ -651,6 +658,7 @@ int vmw_user_dmabuf_synccpu_ioctl(struct drm_device *dev, void *data, dma); ret = vmw_user_dmabuf_synccpu_grab(user_bo, tfile, arg->flags); vmw_dmabuf_unreference(&dma_buf); + ttm_base_object_unref(&buffer_base); if (unlikely(ret != 0 && ret != -ERESTARTSYS && ret != -EBUSY)) { DRM_ERROR("Failed synccpu grab on handle 0x%08x.\n", @@ -692,7 +700,8 @@ int vmw_dmabuf_alloc_ioctl(struct drm_device *dev, void *data, return ret;
ret = vmw_user_dmabuf_alloc(dev_priv, vmw_fpriv(file_priv)->tfile, - req->size, false, &handle, &dma_buf); + req->size, false, &handle, &dma_buf, + NULL); if (unlikely(ret != 0)) goto out_no_dmabuf;
@@ -721,7 +730,8 @@ int vmw_dmabuf_unref_ioctl(struct drm_device *dev, void *data, }
int vmw_user_dmabuf_lookup(struct ttm_object_file *tfile, - uint32_t handle, struct vmw_dma_buffer **out) + uint32_t handle, struct vmw_dma_buffer **out, + struct ttm_base_object **p_base) { struct vmw_user_dma_buffer *vmw_user_bo; struct ttm_base_object *base; @@ -743,7 +753,10 @@ int vmw_user_dmabuf_lookup(struct ttm_object_file *tfile, vmw_user_bo = container_of(base, struct vmw_user_dma_buffer, prime.base); (void)ttm_bo_reference(&vmw_user_bo->dma.base); - ttm_base_object_unref(&base); + if (p_base) + *p_base = base; + else + ttm_base_object_unref(&base); *out = &vmw_user_bo->dma;
return 0; @@ -1004,7 +1017,7 @@ int vmw_dumb_create(struct drm_file *file_priv,
ret = vmw_user_dmabuf_alloc(dev_priv, vmw_fpriv(file_priv)->tfile, args->size, false, &args->handle, - &dma_buf); + &dma_buf, NULL); if (unlikely(ret != 0)) goto out_no_dmabuf;
@@ -1032,7 +1045,7 @@ int vmw_dumb_map_offset(struct drm_file *file_priv, struct vmw_dma_buffer *out_buf; int ret;
- ret = vmw_user_dmabuf_lookup(tfile, handle, &out_buf); + ret = vmw_user_dmabuf_lookup(tfile, handle, &out_buf, NULL); if (ret != 0) return -EINVAL;
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c b/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c index bba1ee3..fd47547 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c @@ -855,7 +855,7 @@ static int vmw_shader_define(struct drm_device *dev, struct drm_file *file_priv,
if (buffer_handle != SVGA3D_INVALID_ID) { ret = vmw_user_dmabuf_lookup(tfile, buffer_handle, - &buffer); + &buffer, NULL); if (unlikely(ret != 0)) { DRM_ERROR("Could not find buffer for shader " "creation.\n"); diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c index 3361769..64b5040 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c @@ -46,6 +46,7 @@ struct vmw_user_surface { struct vmw_surface srf; uint32_t size; struct drm_master *master; + struct ttm_base_object *backup_base; };
/** @@ -656,6 +657,7 @@ static void vmw_user_surface_base_release(struct ttm_base_object **p_base) struct vmw_resource *res = &user_srf->srf.res;
*p_base = NULL; + ttm_base_object_unref(&user_srf->backup_base); vmw_resource_unreference(&res); }
@@ -851,7 +853,8 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data, res->backup_size, true, &backup_handle, - &res->backup); + &res->backup, + &user_srf->backup_base); if (unlikely(ret != 0)) { vmw_resource_unreference(&res); goto out_unlock; @@ -1321,7 +1324,8 @@ int vmw_gb_surface_define_ioctl(struct drm_device *dev, void *data,
if (req->buffer_handle != SVGA3D_INVALID_ID) { ret = vmw_user_dmabuf_lookup(tfile, req->buffer_handle, - &res->backup); + &res->backup, + &user_srf->backup_base); if (ret == 0 && res->backup->base.num_pages * PAGE_SIZE < res->backup_size) { DRM_ERROR("Surface backup buffer is too small.\n"); @@ -1335,7 +1339,8 @@ int vmw_gb_surface_define_ioctl(struct drm_device *dev, void *data, req->drm_surface_flags & drm_vmw_surface_flag_shareable, &backup_handle, - &res->backup); + &res->backup, + &user_srf->backup_base);
if (unlikely(ret != 0)) { vmw_resource_unreference(&res);