Описание
In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Be stricter about IO mapping flags The current panthor_device_mmap_io() implementation has two issues: 1. For mapping DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET, panthor_device_mmap_io() bails if VM_WRITE is set, but does not clear VM_MAYWRITE. That means userspace can use mprotect() to make the mapping writable later on. This is a classic Linux driver gotcha. I don't think this actually has any impact in practice: When the GPU is powered, writes to the FLUSH_ID seem to be ignored; and when the GPU is not powered, the dummy_latest_flush page provided by the driver is deliberately designed to not do any flushes, so the only thing writing to the dummy_latest_flush could achieve would be to make *more* flushes happen. 2. panthor_device_mmap_io() does not block MAP_PRIVATE mappings (which are mappings without the VM_SHARED flag). MAP_PRIVATE in combination with VM_MAYWRITE indicates that the VMA has copy-on-write semantics, which for VM_PFNMAP are semi-supported but fairly cursed. In particular, in such a mapping, the driver can only install PTEs during mmap() by calling remap_pfn_range() (because remap_pfn_range() wants to **store the physical address of the mapped physical memory into the vm_pgoff of the VMA**); installing PTEs later on with a fault handler (as panthor does) is not supported in private mappings, and so if you try to fault in such a mapping, vmf_insert_pfn_prot() splats when it hits a BUG() check. Fix it by clearing the VM_MAYWRITE flag (userspace writing to the FLUSH_ID doesn't make sense) and requiring VM_SHARED (copy-on-write semantics for the FLUSH_ID don't make sense). Reproducers for both scenarios are in the notes of my patch on the mailing list; I tested that these bugs exist on a Rock 5B machine. Note that I only compile-tested the patch, I haven't tested it; I don't have a working kernel build setup for the test machine yet. Please test it before applying it.
Пакеты
| Пакет | Статус | Версия исправления | Релиз | Тип |
|---|---|---|---|---|
| linux | fixed | 6.11.9-1 | package | |
| linux | not-affected | bookworm | package | |
| linux | not-affected | bullseye | package |
Примечания
https://git.kernel.org/linus/f432a1621f049bb207e78363d9d0e3c6fa2da5db (6.12-rc7)
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Be stricter about IO mapping flags The current panthor_device_mmap_io() implementation has two issues: 1. For mapping DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET, panthor_device_mmap_io() bails if VM_WRITE is set, but does not clear VM_MAYWRITE. That means userspace can use mprotect() to make the mapping writable later on. This is a classic Linux driver gotcha. I don't think this actually has any impact in practice: When the GPU is powered, writes to the FLUSH_ID seem to be ignored; and when the GPU is not powered, the dummy_latest_flush page provided by the driver is deliberately designed to not do any flushes, so the only thing writing to the dummy_latest_flush could achieve would be to make *more* flushes happen. 2. panthor_device_mmap_io() does not block MAP_PRIVATE mappings (which are mappings without the VM_SHARED flag). MAP_PRIVATE in combination with VM_MAYWRITE indicates that the VMA has copy-on-writ...
In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Be stricter about IO mapping flags The current panthor_device_mmap_io() implementation has two issues: 1. For mapping DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET, panthor_device_mmap_io() bails if VM_WRITE is set, but does not clear VM_MAYWRITE. That means userspace can use mprotect() to make the mapping writable later on. This is a classic Linux driver gotcha. I don't think this actually has any impact in practice: When the GPU is powered, writes to the FLUSH_ID seem to be ignored; and when the GPU is not powered, the dummy_latest_flush page provided by the driver is deliberately designed to not do any flushes, so the only thing writing to the dummy_latest_flush could achieve would be to make *more* flushes happen. 2. panthor_device_mmap_io() does not block MAP_PRIVATE mappings (which are mappings without the VM_SHARED flag). MAP_PRIVATE in combination with VM_MAYWRITE indicates that the VMA has copy-on-writ...
In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Be stricter about IO mapping flags The current panthor_device_mmap_io() implementation has two issues: 1. For mapping DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET, panthor_device_mmap_io() bails if VM_WRITE is set, but does not clear VM_MAYWRITE. That means userspace can use mprotect() to make the mapping writable later on. This is a classic Linux driver gotcha. I don't think this actually has any impact in practice: When the GPU is powered, writes to the FLUSH_ID seem to be ignored; and when the GPU is not powered, the dummy_latest_flush page provided by the driver is deliberately designed to not do any flushes, so the only thing writing to the dummy_latest_flush could achieve would be to make *more* flushes happen. 2. panthor_device_mmap_io() does not block MAP_PRIVATE mappings (which are mappings without the VM_SHARED flag). MAP_PRIVATE in combination with VM_MAYWRITE indic
In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Be stricter about IO mapping flags The current panthor_device_mmap_io() implementation has two issues: 1. For mapping DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET, panthor_device_mmap_io() bails if VM_WRITE is set, but does not clear VM_MAYWRITE. That means userspace can use mprotect() to make the mapping writable later on. This is a classic Linux driver gotcha. I don't think this actually has any impact in practice: When the GPU is powered, writes to the FLUSH_ID seem to be ignored; and when the GPU is not powered, the dummy_latest_flush page provided by the driver is deliberately designed to not do any flushes, so the only thing writing to the dummy_latest_flush could achieve would be to make *more* flushes happen. 2. panthor_device_mmap_io() does not block MAP_PRIVATE mappings (which are mappings without the VM_SHARED flag). MAP_PRIVATE in combination with VM_MAYWRITE in...
Уязвимость функции panthor_device_mmap_io() модуля drivers/gpu/drm/panthor/panthor_device.c - драйвера поддержки инфраструктуры прямого рендеринга (DRI) ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании