Affected: Alpaquita:25: linux-lts, Alpaquita:stream: linux-lts

In the Linux kernel, the following vulnerability has been resolved:

drm/vmwgfx: avoid destroy_workqueue(NULL) on vkms init failure

Two paths through vmw_vkms_init() can leave vmw->crc_workq NULL while still leaving the rest of the driver in a state that calls vmw_vkms_cleanup() at module unload:

1. vmw_host_get_guestinfo(GUESTINFO_VBLANK, ...) failing or returning an oversized buffer -- the common case on hosts without a VBLANK guestinfo entry -- early-returned before the workqueue allocation. 2. alloc_ordered_workqueue() returning NULL on memory pressure.

vmw_vkms_cleanup() then calls destroy_workqueue(NULL), which dereferences wq->name and panics.

Fix the first case by removing the early return: vmw->vkms_enabled is already false on the rpci-failure path so no work will ever be queued, and allocating the workqueue unconditionally keeps the control flow simple. Fix the second case by guarding the cleanup with a NULL check, since alloc_ordered_workqueue() can still fail under low memory.

In the Linux kernel, the following vulnerability has been resolved:

drm/vmwgfx: avoid destroy_workqueue(NULL) on vkms init failure

Two paths through vmw_vkms_init() can leave vmw->crc_workq NULL while still leaving the rest of the driver in a state that calls vmw_vkms_cleanup() at module unload:

1. vmw_host_get_guestinfo(GUESTINFO_VBLANK, ...) failing or returning an oversized buffer -- the common case on hosts without a VBLANK guestinfo entry -- early-returned before the workqueue allocation. 2. alloc_ordered_workqueue() returning NULL on memory pressure.

vmw_vkms_cleanup() then calls destroy_workqueue(NULL), which dereferences wq->name and panics.

Fix the first case by removing the early return: vmw->vkms_enabled is already false on the rpci-failure path so no work will ever be queued, and allocating the workqueue unconditionally keeps the control flow simple. Fix the second case by guarding the cleanup with a NULL check, since alloc_ordered_workqueue() can still fail under low memory.

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 120 more

In the Linux kernel, the following vulnerability has been resolved: drm/vmwgfx: avoid destroy_workqueue(NULL) on vkms init failure Two paths through vmw_vkms_init() can leave vmw->crc_workq NULL while still leaving the rest of the driver in a state that calls vmw_vkms_cleanup() at module unload: 1. vmw_host_get_guestinfo(GUESTINFO_VBLANK, ...) failing or returning an oversized buffer -- the common case on hosts without a VBLANK guestinfo entry -- early-returned before the workqueue allocation. 2. alloc_ordered_workqueue() returning NULL on memory pressure. vmw_vkms_cleanup() then calls destroy_workqueue(NULL), which dereferences wq->name and panics. Fix the first case by removing the early return: vmw->vkms_enabled is already false on the rpci-failure path so no work will ever be queued, and allocating the workqueue unconditionally keeps the control flow simple. Fix the second case by guarding the cleanup with a NULL check, since alloc_ordered_workqueue() can still fail under low memory.

Ein Angreifer kann mehrere Schwachstellen in Linux Kernel ausnutzen, um einen Denial of Service herbeizuführen oder einen nicht näher spezifizierten Angriff durchzuführen.