In X.Org X server 20.11 through 21.1.16, when a client application uses easystroke for mouse gestures, the main thread modifies various data structures used by the input thread without acquiring a lock, aka a race condition. In particular, AttachDevice in dix/devices.c does not acquire an input lock.
Weakness
The product does not lock or does not correctly lock a resource when the product must have exclusive access to the resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Xorg-server | Ubuntu | devel | * |
| Xorg-server | Ubuntu | esm-infra/xenial | * |
| Xorg-server | Ubuntu | focal | * |
| Xorg-server | Ubuntu | oracular | * |
| Xorg-server | Ubuntu | plucky | * |
| Xorg-server | Ubuntu | questing | * |
| Xorg-server | Ubuntu | resolute | * |
| Xorg-server-hwe-16.04 | Ubuntu | esm-infra/xenial | * |
| Xwayland | Ubuntu | oracular | * |
| Xwayland | Ubuntu | plucky | * |
Potential Mitigations
References
- https://bugs.debian.org/cgi-bin/bugreport.cgi?att=1;bug=1081338;filename=dix-Hold-input-lock-for-AttachDevice.patch;msg=5
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1081338
- https://gitlab.freedesktop.org/xorg/xserver/-/commit/dc7cb45482cea6ccec22d117ca0b489500b4d0a0
- https://gitlab.freedesktop.org/xorg/xserver/-/issues/1260
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1081338