Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:  IB/hfi1: Fix the PIO_CRED credit-return mmap  hfi1_file_mmap()'s PIO_CRED case must hand user space the single credit-return page that holds this context's entry.  That page is the second or third page of the per-node credit-return allocation once the hardware send context index reaches 64 or 128, so the failure below is intermittent: when the entry lands on the first page the offset is zero and everything works.  Two things are wrong.  First, cr_page_offset is a byte offset but .va is a struct credit_return *, so adding it is pointer arithmetic and scales the offset by sizeof(struct credit_return) == 64.  memvirt then lands 256 KiB or 512 KiB past a 10240-byte allocation.  With an IOMMU translating, that address is inside the vmalloc range but in no vm_area, so dma_mmap_coherent() -> iommu_dma_mmap() finds no pages, vmalloc_to_pfn() returns page_to_pfn(NULL), and remap_pfn_range() installs a frame above MAXPHYADDR.  The first user read then takes:    psm2_ep_open_pr: Corrupted page table at address 7a14d007e000   PGD 800000013886a067 P4D 800000013886a067 PUD 13886b067 PMD 13886c067                                             PTE 800049168e911235   Oops: Bad pagetable: 000d [#1] SMP PTI  Second, and still wrong once the arithmetic is corrected, dma_mmap_coherent() describes a whole coherent buffer and selects the page within it with vma->vm_pgoff.  Offsetting cpu_addr has no effect: for a vmap'd allocation iommu_dma_mmap() uses cpu_addr only to locate the vm_area and then maps pages[vm_pgoff], which hfi1_file_mmap() has just set to 0.  User space therefore always receives the first credit-return page, every credit read is for the wrong context, and send PIO stalls forever.  Use the DMA API as intended: pass the base of the allocation with its full length and select the page with vm_pgoff.  A separate length is needed because memlen must keep describing the VMA for the existing size check.  The dma-direct path stays correct as well, since dma_direct_mmap() adds the same vm_pgoff to the base pfn.  Tested on a Dell T7610 (Xeon E5-2650 v2, Intel IOMMU in DMA-FQ mode) against a Threadripper PRO 3995WX peer, both Omni-Path 100.  Before this change psm2_ep_open() Oopses the kernel; with only the arithmetic corrected psm2_ep_open() succeeds but any transfer that uses send PIO hangs, PSM2_SDMA=2 (send PIO disabled) completing normally while PSM2_SDMA=0 (send PIO only) hangs every time.  With this change send PIO, send DMA and the default mixed mode all work.
Data source: kernel.org (416baaa9-dc9f-4396-8d5f-8c081fb06d67)