diff options
author | Mathias Krause <minipli@grsecurity.net> | 2022-01-27 18:34:19 +1000 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-01-27 17:55:20 +0200 |
commit | a0f90c8815706981c483a652a6aefca51a5e191c (patch) | |
tree | 4a6833bd11235602d4c8986c77bfa35936b98fd3 /drivers | |
parent | 626b2dda7651a7c766108db4cdc0825db05b980d (diff) | |
download | linux-a0f90c8815706981c483a652a6aefca51a5e191c.tar.bz2 |
drm/vmwgfx: Fix stale file descriptors on failed usercopy
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")
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 5 | ||||
-rw-r--r-- | drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 33 | ||||
-rw-r--r-- | drivers/gpu/drm/vmwgfx/vmwgfx_fence.c | 2 | ||||
-rw-r--r-- | drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 2 |
4 files changed, 21 insertions, 21 deletions
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h index d6b66636a19b..ea3ecdda561d 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h @@ -1140,15 +1140,14 @@ 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); bool vmw_cmd_describe(const void *buf, u32 *size, char const **cmd); /** diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c index 44ca23b0ea4e..dd2ff441068e 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c @@ -3879,17 +3879,17 @@ int vmw_execbuf_fence_commands(struct drm_file *file_priv, * Also if copying fails, user-space will be unable to signal the fence 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)); @@ -3917,19 +3917,13 @@ vmw_execbuf_copy_fence_user(struct vmw_private *dev_priv, * 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); VMW_DEBUG_USER("Fence copy error. Syncing.\n"); (void) vmw_fence_obj_wait(fence, false, false, VMW_FENCE_WAIT_TIMEOUT); } + + return ret ? -EFAULT : 0; } /** @@ -4266,16 +4260,23 @@ 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; @@ -4293,7 +4294,7 @@ int vmw_execbuf_process(struct drm_file *file_priv, */ vmw_validation_unref_lists(&val_ctx); - 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 c60d395f9e2e..5001b87aebe8 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c @@ -1128,7 +1128,7 @@ 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 4e693e8de2c3..bbd2f4ec08ec 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c @@ -2501,7 +2501,7 @@ void vmw_kms_helper_validation_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 |