On Thu, 2024-11-07 at 22:16 +0800, Qiu-ji Chen wrote:
In line 1854 of the file esas2r_ioctl.c, the function esas2r_process_vda_ioctl() is called with the parameter vi being assigned the value of a->vda_buffer. On line 1892, a->vda_buffer is stored in DMA memory with the statement a->vda_buffer = dma_alloc_coherent(&a->pcid->dev, ..., indicating that the parameter vi passed to the function is also stored in DMA memory. This suggests that the parameter vi could be altered at any time by malicious hardware.
Absent a specific threat (such as TPM with an interposer) this isn't a vector the kernel protects against (we have to believe what hardware says unless we know it to be specifically buggy about something). However, even supposing a PCI Interposer were considered a threat, the answer now is hardware based: SPDM/PCI-IDE.
Regards,
James