drm/msm: RCU-free the scheduler-containing ring and VM objects

Summary

In the Linux kernel, the following vulnerability has been resolved: drm/msm: RCU-free the scheduler-containing ring and VM objects Both struct msm_ringbuffer and struct msm_gem_vm embed a struct drm_gpu_scheduler. msm_ringbuffer_destroy() and the VM free callback msm_gem_vm_free() call drm_sched_fini() on the embedded scheduler and then free the containing object with plain kfree(). drm_sched_fence_get_timeline_name() returns fence->sched->name, and the scheduler fence keeps a .release callback so it is not ops-detached on signalling. A finished fence exported to userspace (the submit out-fence, or a VM_BIND fence, via sync_file / drm_syncobj) keeps pointing at the embedded scheduler after the ring/VM is freed, so a later get_timeline_name() -- reachable unprivileged through SYNC_IOC_FILE_INFO -- dereferences freed slab memory (KASAN slab-use-after-free read). Per the dma-fence lifetime contract the exporter must keep the data backing a signalled fence alive for an RCU grace period. Free the scheduler-containing objects with kfree_rcu() instead of kfree(). Patchwork: https://patchwork.freedesktop.org/patch/750234/

Timeline

1. Oct 6, 2026, 8:44 AM UTCCVE published
2. Oct 19, 2026, 9:15 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 1d8a5ca436ee4a28eec14cb813f790f7cdeeee19 · fixed in d81bf4581903b0cba0698cd4d1c07fc6be21754a; From 1d8a5ca436ee4a28eec14cb813f790f7cdeeee19 · fixed in 713abac5c04ccbae67f9ac68c3921845535388e7; From 1d8a5ca436ee4a28eec14cb813f790f7cdeeee19 · fixed in 01c8d1f385f788f1bbbbb7687c4386d614281218

• Linux Linux

  5.15

• KernelLinux

  From 5.15.0 · fixed in 6.18.54; From 6.19.0 · fixed in 7.2.8

References 3