From: Mathias Krause <minipli@xxxxxxxxxxxxxx>
commit a0f90c8815706981c483a652a6aefca51a5e191c upstream.
A failing usercopy of the fence_rep object will lead to a stale entry in
the file descriptor table as put_unused_fd() won't release it. This
enables userland to refer to a dangling 'file' object through that still
valid file descriptor, leading to all kinds of use-after-free
exploitation scenarios.
Fix this by deferring the call to fd_install() until after the usercopy
has succeeded.
Fixes: c906965dee22 ("drm/vmwgfx: Add export fence to file descriptor support")
[mks: backport to v4.19 and older]
Signed-off-by: Mathias Krause <minipli@xxxxxxxxxxxxxx>
Signed-off-by: Zack Rusin <zackr@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.14, v4.19
---
drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 5 ++--
drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 34 ++++++++++++-------------
drivers/gpu/drm/vmwgfx/vmwgfx_fence.c | 2 +-
drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 2 +-
4 files changed, 21 insertions(+), 22 deletions(-)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index 1abe21758b0d..bca0b8980c0e 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -855,15 +855,14 @@ extern int vmw_execbuf_fence_commands(struct drm_file *file_priv,
struct vmw_private *dev_priv,
struct vmw_fence_obj **p_fence,
uint32_t *p_handle);
-extern void vmw_execbuf_copy_fence_user(struct vmw_private *dev_priv,
+extern int vmw_execbuf_copy_fence_user(struct vmw_private *dev_priv,
struct vmw_fpriv *vmw_fp,
int ret,
struct drm_vmw_fence_rep __user
*user_fence_rep,
struct vmw_fence_obj *fence,
uint32_t fence_handle,
- int32_t out_fence_fd,
- struct sync_file *sync_file);
+ int32_t out_fence_fd);
extern int vmw_validate_single_buffer(struct vmw_private *dev_priv,
struct ttm_buffer_object *bo,
bool interruptible,
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index f0ab6b2313bb..4c2fc669238c 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -3868,20 +3868,19 @@ int vmw_execbuf_fence_commands(struct drm_file *file_priv,
* object so we wait for it immediately, and then unreference the
* user-space reference.
*/
-void
+int
vmw_execbuf_copy_fence_user(struct vmw_private *dev_priv,
struct vmw_fpriv *vmw_fp,
int ret,
struct drm_vmw_fence_rep __user *user_fence_rep,
struct vmw_fence_obj *fence,
uint32_t fence_handle,
- int32_t out_fence_fd,
- struct sync_file *sync_file)
+ int32_t out_fence_fd)
{
struct drm_vmw_fence_rep fence_rep;
if (user_fence_rep == NULL)
- return;
+ return 0;
memset(&fence_rep, 0, sizeof(fence_rep));
@@ -3909,20 +3908,14 @@ vmw_execbuf_copy_fence_user(struct vmw_private *dev_priv,
* and unreference the handle.
*/
if (unlikely(ret != 0) && (fence_rep.error == 0)) {
- if (sync_file)
- fput(sync_file->file);
-
- if (fence_rep.fd != -1) {
- put_unused_fd(fence_rep.fd);
- fence_rep.fd = -1;
- }
-
ttm_ref_object_base_unref(vmw_fp->tfile,
fence_handle, TTM_REF_USAGE);
DRM_ERROR("Fence copy error. Syncing.\n");
(void) vmw_fence_obj_wait(fence, false, false,
VMW_FENCE_WAIT_TIMEOUT);
}
+
+ return ret ? -EFAULT : 0;
}
/**
@@ -4282,16 +4275,23 @@ int vmw_execbuf_process(struct drm_file *file_priv,
(void) vmw_fence_obj_wait(fence, false, false,
VMW_FENCE_WAIT_TIMEOUT);
+ }
+ }
+
+ ret = vmw_execbuf_copy_fence_user(dev_priv, vmw_fpriv(file_priv), ret,
+ user_fence_rep, fence, handle, out_fence_fd);
+
+ if (sync_file) {
+ if (ret) {
+ /* usercopy of fence failed, put the file object */
+ fput(sync_file->file);
+ put_unused_fd(out_fence_fd);
} else {
/* Link the fence with the FD created earlier */
fd_install(out_fence_fd, sync_file->file);
}
}
- vmw_execbuf_copy_fence_user(dev_priv, vmw_fpriv(file_priv), ret,
- user_fence_rep, fence, handle,
- out_fence_fd, sync_file);
-
/* Don't unreference when handing fence out */
if (unlikely(out_fence != NULL)) {
*out_fence = fence;
@@ -4310,7 +4310,7 @@ int vmw_execbuf_process(struct drm_file *file_priv,
*/
vmw_resource_list_unreference(sw_context, &resource_list);
- return 0;
+ return ret;
out_unlock_binding:
mutex_unlock(&dev_priv->binding_mutex);
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
index 3d546d409334..72a75316d472 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
@@ -1169,7 +1169,7 @@ int vmw_fence_event_ioctl(struct drm_device *dev, void *data,
}
vmw_execbuf_copy_fence_user(dev_priv, vmw_fp, 0, user_fence_rep, fence,
- handle, -1, NULL);
+ handle, -1);
vmw_fence_obj_unreference(&fence);
return 0;
out_no_create:
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index 6a712a8d59e9..248d92c85cf6 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -2662,7 +2662,7 @@ void vmw_kms_helper_buffer_finish(struct vmw_private *dev_priv,
if (file_priv)
vmw_execbuf_copy_fence_user(dev_priv, vmw_fpriv(file_priv),
ret, user_fence_rep, fence,
- handle, -1, NULL);
+ handle, -1);
if (out_fence)
*out_fence = fence;
else
--
2.32.0
