In the Linux kernel, the following vulnerability has been resolved: drm/lima: call drm_mm_init() with a valid allocation range lima_vm_create() is currently run before va_start and va_end are set up, meaning they are both 0

Overview

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

drm/lima: call drm_mm_init() with a valid allocation range

lima_vm_create() is currently run before va_start and va_end are set up, meaning they are both 0. lima_vm_create() runs drm_mm_init() with them as arguments for the allocator, and if DRM_DEBUG_MM is enabled the DRM_MM_BUG_ON check in drm_mm_init then fires, as seen here on exynos4412-odroid-u2:

[ 1.736297] ------------[ cut here ]------------ [ 1.740370] kernel BUG at drivers/gpu/drm/drm_mm.c:931! [ 1.745574] Internal error: Oops - BUG: 0 [#1] SMP ARM [ 1.750697] Modules linked in: [ 1.753734] CPU: 0 UID: 0 PID: 41 Comm: kworker/u16:1 Not tainted 7.0.10-postmarketos-exynos4 #11 PREEMPT [ 1.763372] Hardware name: Samsung Exynos (Flattened Device Tree) [ 1.769446] Workqueue: events_unbound deferred_probe_work_func [ 1.775261] PC is at drm_mm_init+0x9c/0xa4 [ 1.779339] LR is at lima_vm_create+0x144/0x17c [ ... ]

Fix the issue by moving the lima_vm_create() call after va_start and va_end are set up.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.