CVE-2026-98216: IB/hfi1: Fix the PIO_CRED credit-return mmap

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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.

The Linux kernel CVE team has assigned CVE-2026-98216 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.3 with commit 1ec82317a1daac78c04b0c15af89018ccf9fa2b7 and fixed in 6.6.158 with commit 535530bb2ea5254e1e9f55280143d262dd065204
	Issue introduced in 6.3 with commit 1ec82317a1daac78c04b0c15af89018ccf9fa2b7 and fixed in 6.12.112 with commit dcebe0b0bb080a25fe08011fd6b6e741f7912f01
	Issue introduced in 6.3 with commit 1ec82317a1daac78c04b0c15af89018ccf9fa2b7 and fixed in 6.18.54 with commit 180752deb7270ad37394ab6ef7cf4978fad040b3
	Issue introduced in 6.3 with commit 1ec82317a1daac78c04b0c15af89018ccf9fa2b7 and fixed in 7.2.8 with commit bafeac9ce5d1ce5256bcf7e5702e831e9aaf419b
	Issue introduced in 6.3 with commit 1ec82317a1daac78c04b0c15af89018ccf9fa2b7 and fixed in 7.3-rc4 with commit 62f0f34fbd2b2d5653d33d3b9d42fdcabb1c0101

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-98216
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/infiniband/hw/hfi1/file_ops.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/535530bb2ea5254e1e9f55280143d262dd065204
	https://git.kernel.org/stable/c/dcebe0b0bb080a25fe08011fd6b6e741f7912f01
	https://git.kernel.org/stable/c/180752deb7270ad37394ab6ef7cf4978fad040b3
	https://git.kernel.org/stable/c/bafeac9ce5d1ce5256bcf7e5702e831e9aaf419b
	https://git.kernel.org/stable/c/62f0f34fbd2b2d5653d33d3b9d42fdcabb1c0101