drm/vc4: txp: fix writeback dimension checks and normalize rotation#7292
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name2965 wants to merge 1 commit intoraspberrypi:rpi-6.12.yfrom
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drm/vc4: txp: fix writeback dimension checks and normalize rotation#7292name2965 wants to merge 1 commit intoraspberrypi:rpi-6.12.yfrom
name2965 wants to merge 1 commit intoraspberrypi:rpi-6.12.yfrom
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If the rotation value is 0, the rotation is compared to an accurate bitmask, which can bypass the size check, and the frame buffer size validation is too weak to reliably reject write buffers that are too small. Therefore, to prevent this, normalize the rotation state, modify the size check, and reject write targets that cannot cover the programmed output size. Signed-off-by: Jeongjun Park <aha310510@gmail.com>
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If the rotation value is 0, it can be compared to an accurate bitmask, thereby bypassing size validation; furthermore, frame buffer size validation is so inadequate that it cannot reliably filter out write buffers that are too small.
This results in a DMA OOB vulnerability on Raspberry Pi models prior to the 5 that lack an IOMMU, and I have successfully reproduced this vulnerability.
I tested this immediately by installing the Raspberry Pi OS 64-bit on a Raspberry Pi 4 Model B rev 1.2 using Imager.
This issue occurs on Raspberry Pi without IOMMU, and DMA OOB can be easily reproduced in any kernel version where vulnerable code exists, in addition to the kernel version I reproduced.
repro.mp4