[PATCH 4.1 80/86] drm/vmwgfx: Fix up user_dmabuf refcounting

Greg Kroah-Hartman
2015-11-06T19:41:32Z

From: Thomas Hellstrom <thellstrom@vmware.com>

commit 54c12bc374408faddbff75dbf1a6167c19af39c4 upstream.

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.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 3 +++
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 | 12 +++++++++---
7 files changed, 43 insertions(+), 17 deletions(-)

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -1458,6 +1458,9 @@ static void __exit vmwgfx_exit(void)
drm_pci_exit(&driver, &vmw_pci_driver);
}

+MODULE_INFO(vmw_patch, "ed7d78b2");
+MODULE_INFO(vmw_patch, "54c12bc3");
+
module_init(vmwgfx_init);
module_exit(vmwgfx_exit);

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -636,7 +636,8 @@ extern int vmw_user_dmabuf_alloc(struct
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);
@@ -650,7 +651,8 @@ extern uint32_t vmw_dmabuf_validate_node
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,
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -887,7 +887,8 @@ static int vmw_translate_mob_ptr(struct
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;
@@ -949,7 +950,8 @@ static int vmw_translate_guest_ptr(struc
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;
--- 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
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;

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -356,7 +356,7 @@ int vmw_user_lookup_handle(struct vmw_pr
}

*out_surf = NULL;
- ret = vmw_user_dmabuf_lookup(tfile, handle, out_buf);
+ ret = vmw_user_dmabuf_lookup(tfile, handle, out_buf, NULL);
return ret;
}

@@ -483,7 +483,8 @@ int vmw_user_dmabuf_alloc(struct vmw_pri
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;
@@ -517,6 +518,10 @@ int vmw_user_dmabuf_alloc(struct vmw_pri
}

*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:
@@ -633,6 +638,7 @@ int vmw_user_dmabuf_synccpu_ioctl(struct
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
@@ -645,7 +651,8 @@ int vmw_user_dmabuf_synccpu_ioctl(struct

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;

@@ -653,6 +660,7 @@ int vmw_user_dmabuf_synccpu_ioctl(struct
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",
@@ -694,7 +702,8 @@ int vmw_dmabuf_alloc_ioctl(struct drm_de
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;

@@ -723,7 +732,8 @@ int vmw_dmabuf_unref_ioctl(struct drm_de
}

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;
@@ -745,7 +755,10 @@ int vmw_user_dmabuf_lookup(struct ttm_ob
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;
@@ -1006,7 +1019,7 @@ int vmw_dumb_create(struct drm_file *fil

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;

@@ -1034,7 +1047,7 @@ int vmw_dumb_map_offset(struct drm_file
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;

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_shader.c
@@ -470,7 +470,7 @@ int vmw_shader_define_ioctl(struct drm_d

if (arg->buffer_handle != SVGA3D_INVALID_ID) {
ret = vmw_user_dmabuf_lookup(tfile, arg->buffer_handle,
- &buffer);
+ &buffer, NULL);
if (unlikely(ret != 0)) {
DRM_ERROR("Could not find buffer for shader "
"creation.\n");
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -43,6 +43,7 @@ struct vmw_user_surface {
struct vmw_surface srf;
uint32_t size;
struct drm_master *master;
+ struct ttm_base_object *backup_base;
};

/**
@@ -652,6 +653,8 @@ static void vmw_user_surface_base_releas
struct vmw_resource *res = &user_srf->srf.res;

*p_base = NULL;
+ if (user_srf->backup_base)
+ ttm_base_object_unref(&user_srf->backup_base);
vmw_resource_unreference(&res);
}

@@ -846,7 +849,8 @@ int vmw_surface_define_ioctl(struct drm_
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;
@@ -1309,7 +1313,8 @@ int vmw_gb_surface_define_ioctl(struct d

if (req->buffer_handle != SVGA3D_INVALID_ID) {
ret = vmw_user_dmabuf_lookup(tfile, req->buffer_handle,
- &res->backup);
+ &res->backup,
+ &user_srf->backup_base);
} else if (req->drm_surface_flags &
drm_vmw_surface_flag_create_buffer)
ret = vmw_user_dmabuf_alloc(dev_priv, tfile,
@@ -1317,7 +1322,8 @@ int vmw_gb_surface_define_ioctl(struct d
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);